How to find the solution to an equation - PSAT Math
Card 0 of 399
√(3x) = 9
What is x?
√(3x) = 9
What is x?
Tap to see back →
To solve, remove the radical by squaring both sides
(√3x) 2 = 92
3x = 81
x = 81/3 = 27
To solve, remove the radical by squaring both sides
(√3x) 2 = 92
3x = 81
x = 81/3 = 27
√(8y) + 18 = 4
What is y?
√(8y) + 18 = 4
What is y?
Tap to see back →
First, simplify the equation:
√(8y) + 18 = 4
√(8y) = -14
Then square both sides
(√8y) 2 = -142
8y = 196
y = 196/8 = 24.5
First, simplify the equation:
√(8y) + 18 = 4
√(8y) = -14
Then square both sides
(√8y) 2 = -142
8y = 196
y = 196/8 = 24.5
If y = 4 and 6y = 10z + y, then z = ?
If y = 4 and 6y = 10z + y, then z = ?
Tap to see back →
- Substitute y in the equation for 4.
- You now have 6 * 4 = 10z + 4
- Simplify the equation: 24 = 10z + 4
- Subtract 4 from both sides: 24 – 4 = 10z + 4 – 4
- You now have 20 = 10z
- Divde both sides by 10 to solve for z.
- z = 2.
- Substitute y in the equation for 4.
- You now have 6 * 4 = 10z + 4
- Simplify the equation: 24 = 10z + 4
- Subtract 4 from both sides: 24 – 4 = 10z + 4 – 4
- You now have 20 = 10z
- Divde both sides by 10 to solve for z.
- z = 2.
A sequence of numbers is: 2, 5, 8, 11. Assuming it follows the same pattern, what would be the value of the 20th number?
A sequence of numbers is: 2, 5, 8, 11. Assuming it follows the same pattern, what would be the value of the 20th number?
Tap to see back →
This goes up at a constant number between values, making it an arthmetic sequence. The first number is 2, with a difference of 3. Plugging this into the arithmetic equation you get An = 2 + 3 (n – 1). Plugging in 20 for n, you get a value of 59.
This goes up at a constant number between values, making it an arthmetic sequence. The first number is 2, with a difference of 3. Plugging this into the arithmetic equation you get An = 2 + 3 (n – 1). Plugging in 20 for n, you get a value of 59.
The first four numbers of a sequence are 5, 10, 20, 40. Assuming the pattern continues, what is the 6th term of the sequence?
The first four numbers of a sequence are 5, 10, 20, 40. Assuming the pattern continues, what is the 6th term of the sequence?
Tap to see back →
Looking at the sequence you can see that it doubles each term, making it a geometric sequence. Since it doubles r = 2 and the first term is 5. Plugging this into the geometric equation you get An = 5(2)n–1. Setting n = 6, you get 160 as the 6th term.
Looking at the sequence you can see that it doubles each term, making it a geometric sequence. Since it doubles r = 2 and the first term is 5. Plugging this into the geometric equation you get An = 5(2)n–1. Setting n = 6, you get 160 as the 6th term.
Given f(x) = x2 – 9. What are the zeroes of the function?
Given f(x) = x2 – 9. What are the zeroes of the function?
Tap to see back →
The zeroes of the equation are where f(x) = 0 (aka x-intercepts). Setting the equation equal to zero you get x2 = 9. Since a square makes a negative number positive, x can be equal to 3 or –3.
The zeroes of the equation are where f(x) = 0 (aka x-intercepts). Setting the equation equal to zero you get x2 = 9. Since a square makes a negative number positive, x can be equal to 3 or –3.
Give the lines y = 0.5x+3 and y=3x-2. What is the y value of the point of intersection?
Give the lines y = 0.5x+3 and y=3x-2. What is the y value of the point of intersection?
Tap to see back →
In order to solve for the x value you set both equations equal to each other (0.5x+3=3x-2). This gives you the x value for the point of intersection at x=2. Plugging x=2 into either equation gives you y=4.
In order to solve for the x value you set both equations equal to each other (0.5x+3=3x-2). This gives you the x value for the point of intersection at x=2. Plugging x=2 into either equation gives you y=4.
If 6_x_ = 42 and xk = 2, what is the value of k?
If 6_x_ = 42 and xk = 2, what is the value of k?
Tap to see back →
Solve the first equation for x by dividing both sides of the equation by 6; the result is 7. Solve the second equation for k by dividing both sides of the equation by x, which we now know is 7. The result is 2/7.
Solve the first equation for x by dividing both sides of the equation by 6; the result is 7. Solve the second equation for k by dividing both sides of the equation by x, which we now know is 7. The result is 2/7.
If 4_x_ + 5 = 13_x_ + 4 – x – 9, then x = ?
If 4_x_ + 5 = 13_x_ + 4 – x – 9, then x = ?
Tap to see back →
Start by combining like terms.
4_x_ + 5 = 13_x_ + 4 – x – 9
4_x_ + 5 = 12_x_ – 5
–8_x_ = –10
x = 5/4
Start by combining like terms.
4_x_ + 5 = 13_x_ + 4 – x – 9
4_x_ + 5 = 12_x_ – 5
–8_x_ = –10
x = 5/4
If 3 – 3_x_ < 20, which of the following could not be a value of x?
If 3 – 3_x_ < 20, which of the following could not be a value of x?
Tap to see back →
First we solve for x.
Subtracting 3 from both sides gives us –3_x_ < 17.
Dividing by –3 gives us x > –17/3.
–6 is less than –17/3.
First we solve for x.
Subtracting 3 from both sides gives us –3_x_ < 17.
Dividing by –3 gives us x > –17/3.
–6 is less than –17/3.
Let x be a number. Increasing x by twenty percent yields that same result as decreasing the product of four and x by five. What is x?
Let x be a number. Increasing x by twenty percent yields that same result as decreasing the product of four and x by five. What is x?
Tap to see back →
The problem tells us that increasing x by twenty percent gives us the same thing that we would get if we decreased the product of four and x by five. We need to find expressions for these two situations, and then we can set them equal and solve for x.
Let's find an expression for increasing x by twenty percent. We could represent this as x + 20%x = x + 0.2x = 1.2x = 6x/5.
Let's find an expression for decreasing the product of four and x by five. First, we must find the product of four and x, which can be written as 4x. Then we must decrease this by five, so we must subtract five from 4x, which could be written as 4x - 5.
Now we must set the two expressions equal to one another.
6x/5 = 4x - 5
Subtract 6x/5 from both sides. We can rewrite 4x as 20x/5 so that it has a common denominator with 6x/5.
0 = 20x/5 - 6x/5 - 5 = 14x/5 - 5
0 = 14x/5 - 5
Now we can add five to both sides.
5 = 14x/5
Now we can multiply both sides by 5/14, which is the reciprocal of 14/5.
5(5/14) = (14x/5)(5/14) = x
25/14 = x
The answer is 25/14.
The problem tells us that increasing x by twenty percent gives us the same thing that we would get if we decreased the product of four and x by five. We need to find expressions for these two situations, and then we can set them equal and solve for x.
Let's find an expression for increasing x by twenty percent. We could represent this as x + 20%x = x + 0.2x = 1.2x = 6x/5.
Let's find an expression for decreasing the product of four and x by five. First, we must find the product of four and x, which can be written as 4x. Then we must decrease this by five, so we must subtract five from 4x, which could be written as 4x - 5.
Now we must set the two expressions equal to one another.
6x/5 = 4x - 5
Subtract 6x/5 from both sides. We can rewrite 4x as 20x/5 so that it has a common denominator with 6x/5.
0 = 20x/5 - 6x/5 - 5 = 14x/5 - 5
0 = 14x/5 - 5
Now we can add five to both sides.
5 = 14x/5
Now we can multiply both sides by 5/14, which is the reciprocal of 14/5.
5(5/14) = (14x/5)(5/14) = x
25/14 = x
The answer is 25/14.
If 4_xs = v, v = ks , and sv ≠_ 0, which of the following is equal to k ?
If 4_xs = v, v = ks , and sv ≠_ 0, which of the following is equal to k ?
Tap to see back →
This question gives two equalities and one inequality. The inequality (sv ≠ 0) simply says that neither s nor v is 0. The two equalities tell us that 4_xs and ks are both equal to v, which means that 4_xs_ and ks must be equal to each other--that is, 4_xs_ = ks. Dividing both sides by s gives 4_x_ = k, which is our solution.
This question gives two equalities and one inequality. The inequality (sv ≠ 0) simply says that neither s nor v is 0. The two equalities tell us that 4_xs and ks are both equal to v, which means that 4_xs_ and ks must be equal to each other--that is, 4_xs_ = ks. Dividing both sides by s gives 4_x_ = k, which is our solution.
Luke purchased a tractor for $1200. The value of the tractor decreases by 25 percent each year. The value,
, in dollars, of the tractor at
years from the date of purchase is given by the function
.
In how many years from the date of purchase will the value of the tractor be $675?
Luke purchased a tractor for $1200. The value of the tractor decreases by 25 percent each year. The value, , in dollars, of the tractor at
years from the date of purchase is given by the function
.
In how many years from the date of purchase will the value of the tractor be $675?
Tap to see back →
We are looking for the value of t that gives $675 as the result when plugged in V (t ). While there are many ways to do this, one of the fastest is to plug in the answer choices as values of t .
When we plug t = 1 into _V (_t ), we get V (1) = 1200(0.75)1 = 1000(0.75) = $900, which is incorrect.
When we plug t = 2 into V (t ), we get V (2) = 1200(0.75)2 = $675, so this is our solution.
The value of the tractor will be $675 after 2 years.
Finally, we can see that if t = 3, 4, or 5, the resulting values of the V (t ) are all incorrect.
We are looking for the value of t that gives $675 as the result when plugged in V (t ). While there are many ways to do this, one of the fastest is to plug in the answer choices as values of t .
When we plug t = 1 into _V (_t ), we get V (1) = 1200(0.75)1 = 1000(0.75) = $900, which is incorrect.
When we plug t = 2 into V (t ), we get V (2) = 1200(0.75)2 = $675, so this is our solution.
The value of the tractor will be $675 after 2 years.
Finally, we can see that if t = 3, 4, or 5, the resulting values of the V (t ) are all incorrect.
If 2x2(5-x)(3x+2) = 0, then what is the sum of all of the possible values of x?
If 2x2(5-x)(3x+2) = 0, then what is the sum of all of the possible values of x?
Tap to see back →
Since we are told that 2x2(5-x)(3x+2) = 0, in order to find x, we must let each of the factors of our equation equal zero. The equation is already factored for us, which means that our factors are 2x2, (5-x), and (3x+2). We must let each of these equal zero separately, and these will give us the possible values of x that satisfy the equation.
Let's look at the factor 2x2 and set it equal to zero.
2x2 = 0
x = 0
Then, let's look at the factor 5-x.
5-x = 0
Add x to both sides
5 = x
x = 5
Finally, we set the last factor equal to zero.
(3x+2) = 0
Subtract two from both sides
3x = -2
Divide both sides by three.
x = -2/3
This means that the possible values of x are 0, 5, or -2/3. The question asks us to find the sum of these values.
0 + 5 + -2/3
5 + -2/3
Remember to find a common denominator of 3.
15/3 + -2/3 = 13/3.
The answer is 13/3.
Since we are told that 2x2(5-x)(3x+2) = 0, in order to find x, we must let each of the factors of our equation equal zero. The equation is already factored for us, which means that our factors are 2x2, (5-x), and (3x+2). We must let each of these equal zero separately, and these will give us the possible values of x that satisfy the equation.
Let's look at the factor 2x2 and set it equal to zero.
2x2 = 0
x = 0
Then, let's look at the factor 5-x.
5-x = 0
Add x to both sides
5 = x
x = 5
Finally, we set the last factor equal to zero.
(3x+2) = 0
Subtract two from both sides
3x = -2
Divide both sides by three.
x = -2/3
This means that the possible values of x are 0, 5, or -2/3. The question asks us to find the sum of these values.
0 + 5 + -2/3
5 + -2/3
Remember to find a common denominator of 3.
15/3 + -2/3 = 13/3.
The answer is 13/3.
If bx + c = e – ax, then what is x?
If bx + c = e – ax, then what is x?
Tap to see back →
To solve for x:
bx + c = e – ax
bx + ax = e – c
x(b+a) = e-c
x = (e-c) / (b+a)
To solve for x:
bx + c = e – ax
bx + ax = e – c
x(b+a) = e-c
x = (e-c) / (b+a)
Solve for
:

Solve for :
Tap to see back →
First combine like terms. In this case, 4x and 9x can be added together:
13x + 13 = 0
Subtract 13 from both sides:
13x = -13
Divide both sides by 13 to isolate x:
x = -13/13
x = -1
First combine like terms. In this case, 4x and 9x can be added together:
13x + 13 = 0
Subtract 13 from both sides:
13x = -13
Divide both sides by 13 to isolate x:
x = -13/13
x = -1
√( x2 -7) = 3
What is x?
√( x2 -7) = 3
What is x?
Tap to see back →
To solve, remove the radical by squaring both sides
(√( x2 -7)) 2 = 32
x2 -7 = 9
x2 = 16
x = 4
To solve, remove the radical by squaring both sides
(√( x2 -7)) 2 = 32
x2 -7 = 9
x2 = 16
x = 4
Tommy's and Sara's current ages are represented by t and s, respectively. If in five years, Tommy will be twice as old as Sara, which of the following represents t in terms of s?
Tommy's and Sara's current ages are represented by t and s, respectively. If in five years, Tommy will be twice as old as Sara, which of the following represents t in terms of s?
Tap to see back →
Tommy's current age is represented by t, and Sara's is represented by s. In five years, both Tommy's and Sara's ages will be increased by five. Thus, in five years, we can represent Tommy's age as
and Sara's as
.
The problem tells us that Tommy's age in five years will be twice as great as Sara's in five years. Thus, we can write an algebraic expression to represent the problem as follows:

In order to solve for t, first simplify the right side by distributing the 2.

Then subtract 5 from both sides.

The answer is
.
Tommy's current age is represented by t, and Sara's is represented by s. In five years, both Tommy's and Sara's ages will be increased by five. Thus, in five years, we can represent Tommy's age as and Sara's as
.
The problem tells us that Tommy's age in five years will be twice as great as Sara's in five years. Thus, we can write an algebraic expression to represent the problem as follows:
In order to solve for t, first simplify the right side by distributing the 2.
Then subtract 5 from both sides.
The answer is .
10 gallons of paint will cover 75 ft2. How many gallons of paint will be required to paint the area of a rectangular wall that has a height of 8 ft and a length of 24 ft?
10 gallons of paint will cover 75 ft2. How many gallons of paint will be required to paint the area of a rectangular wall that has a height of 8 ft and a length of 24 ft?
Tap to see back →
First we need the area or the rectangle. 24 * 8 = 192. So now we know that 10 gallons will cover 75 ft2 and x gallons will cover 192 ft2. We set up a simple ratio and cross multiply to find that 75_x_ = 1920.
x = 25.6
First we need the area or the rectangle. 24 * 8 = 192. So now we know that 10 gallons will cover 75 ft2 and x gallons will cover 192 ft2. We set up a simple ratio and cross multiply to find that 75_x_ = 1920.
x = 25.6
What number decreased by 7 is equal to 10 increased by 7?
What number decreased by 7 is equal to 10 increased by 7?
Tap to see back →
The best way to solve this problem is to translate it into an equation, "decreased" meaning subtract and "increased" meaning add:
x – 7 = 10 + 7
x = 24
The best way to solve this problem is to translate it into an equation, "decreased" meaning subtract and "increased" meaning add:
x – 7 = 10 + 7
x = 24