Algebra 1 : Systems of Equations

Study concepts, example questions & explanations for Algebra 1

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Example Questions

Example Question #3 : Solving Equations And Inequallities

Solve for \displaystyle x:

\displaystyle 8x-5-4x=-x+10

Possible Answers:

\displaystyle 2

\displaystyle 4

\displaystyle 6

\displaystyle 5

\displaystyle 3

Correct answer:

\displaystyle 3

Explanation:

\displaystyle 8x-5-4x=-x+10 can be simplified to become

\displaystyle 4x-5=-x+10

Then, you can further simplify by adding 5 and \displaystyle x to both sides to get \displaystyle 5x=15.

Then, you can divide both sides by 5 to get \displaystyle x=3.

Example Question #1 : Systems Of Equations

What number is six less than eight more than one half of four times the square of the greatest negative integer?

Possible Answers:

\displaystyle 0

\displaystyle 4

\displaystyle -6

\displaystyle \frac{1}{3}

\displaystyle 11

Correct answer:

\displaystyle 4

Explanation:

Turn the word problem into math.  Start at the end--what is the greatest negative integer?  -1!

\displaystyle (-1)^2\cdot4\cdot\frac{1}{2}+8-6=1\cdot4\cdot\frac{1}{2}+8-6=2+8-6=4

Example Question #2 : Systems Of Equations

\displaystyle 18\div\frac{1}{6}\cdot\frac{9}{72}\cdot\frac{4}{27}\cdot(-8+7)^9=

Possible Answers:

\displaystyle -6

\displaystyle -2

\displaystyle 6

\displaystyle -12

\displaystyle 9

Correct answer:

\displaystyle -2

Explanation:

\displaystyle 18\div\frac{1}{6}\cdot\frac{9}{72}\cdot\frac{4}{27}\cdot(-8+7)^9=18\cdot6\cdot\frac{1}{8}\cdot\frac{4}{27}\cdot-1

 

Remember to cancel as you go--the 18 will cancel with the 27, the 4 will cancel with the 8, and so on:

\displaystyle 18\cdot6\cdot\frac{1}{8}\cdot\frac{4}{27}\cdot-1= 2\cdot6\cdot\frac{1}{2}\cdot\frac{1}{3}\cdot-1

 

Continue to reduce:

 

\displaystyle 2\cdot6\cdot\frac{1}{2}\cdot\frac{1}{3}\cdot-1= 2\cdot1\cdot-1=-2

Example Question #1 : How To Find The Solution To An Equation

Solve for \displaystyle x:

\displaystyle 6x-1=12x+8-3x

Possible Answers:

\displaystyle -3

\displaystyle -6

\displaystyle 1

\displaystyle 6

\displaystyle 3

Correct answer:

\displaystyle -3

Explanation:

To solve for \displaystyle x, you must first combine the \displaystyle x's on the right side of the equation. This will give you \displaystyle \ 6x-1=9x+8.

Then, subtract \displaystyle 8 and \displaystyle 6x from both sides of the equation to get \displaystyle -9=3x.

Finally, divide both sides by \displaystyle 3 to get the solution \displaystyle x=-3.

Example Question #3 : How To Find The Solution To An Equation

Solve for \displaystyle x:

\displaystyle 3x+5=2(3x-2)

Possible Answers:

\displaystyle -2

\displaystyle -3

\displaystyle 3

\displaystyle 1

\displaystyle 2

Correct answer:

\displaystyle 3

Explanation:

First, use the distributive property to simplify the right side of the equation: \displaystyle 3x+5=6x-4. Then, subtract \displaystyle 3x and add 4 to both sides to separate the \displaystyle x's and the integers to get \displaystyle 9=3x. Divide both sides by 3 to get \displaystyle x=3.

Example Question #4 : How To Find The Solution To An Equation

Solve for \displaystyle x:

\displaystyle a(x+b)= c

Possible Answers:

\displaystyle \frac{a}{c}-b

\displaystyle \frac{a}{c-b}

\displaystyle \frac{c-b}{a}

\displaystyle \frac{c}{a}-b

\displaystyle \frac{a-b}{c}

Correct answer:

\displaystyle \frac{c}{a}-b

Explanation:

To solve for \displaystyle x, first divide both sides by \displaystyle a: \displaystyle x+b=\frac{c}{a}. Then, subtract both sides by \displaystyle b to get \displaystyle x=\frac{c}{a}-b.

Example Question #3 : How To Find The Solution To An Equation

\displaystyle (4^2)^x=64

Possible Answers:

\displaystyle -2

\displaystyle 4

\displaystyle -\frac{3}{4}

\displaystyle 2

\displaystyle \frac{3}{2}

Correct answer:

\displaystyle \frac{3}{2}

Explanation:

\displaystyle (4^2)^x= 4^{2x}=64

\displaystyle 64= 4\cdot 4\cdot 4=4^3

\displaystyle 4^{2x}=4^3

\displaystyle 2x = 3

\displaystyle x = \frac{3}2{}

Example Question #2 : Systems Of Equations

\displaystyle \frac{4^2+6\cdot 9}{4+3(2)}+\frac{7}{14}\cdot\frac{50}{25}-1=

Possible Answers:

\displaystyle 7

\displaystyle 8

\displaystyle 12

\displaystyle 19.8

\displaystyle 9

Correct answer:

\displaystyle 7

Explanation:

1.  First simplify the first expression:

 

\displaystyle \frac{4^2 +6\cdot 9}{4+3(2)}=\frac{4\cdot 4+54}{4+6}=\frac{16+54}{10}=\frac{70}{10}=7

 

2.  Then, simplify the next two expressions:

\displaystyle \frac{7}{14}\cdot\frac{50}{25}=\frac{1}{2}\cdot\frac{2}{1}=1

 

3.  Finally, add and subtract:

\displaystyle 7+1-1=7

Example Question #7 : How To Find The Solution To An Equation

Solve for x.

\displaystyle \frac{x^2-x^3-(-x-4)}{\frac{1}{x}+\frac{x}{1}}, x=-2

Possible Answers:

\displaystyle \frac{-7}{9}

\displaystyle \frac{28}{3}

\displaystyle \frac{-4}{3}

\displaystyle 12

\displaystyle \frac{-28}{5}

Correct answer:

\displaystyle \frac{-28}{5}

Explanation:

1.  First solve for the numerator by plugging in -2 for x:

\displaystyle (-2)^2-(-2)^3-(-(-2)-4)=4+8+2= 14

2.  Then, solve the denominator by combining the fractions:

\displaystyle \frac{1}{x}+\frac{x}{1}= \frac{-1}{2}+\frac{-2}{1}=\frac{-1}{2}+\frac{-4}{2}=\frac{-5}{2}

3.  Finally, "rationalize" the complex fraction by multiplying top and bottom by -2/5:

\displaystyle \frac{14}{\frac{-5}{2}}\cdot\frac{\frac{-2}{5}}{\frac{-2}{5}}=\frac{\frac{-28}{5}}{1}=\frac{-28}{5}

Example Question #8 : How To Find The Solution To An Equation

\displaystyle \frac{x*7+5*4+1}{y*2+4}=3

If x/y is equivalent to 12/20, what is the value of x?

Possible Answers:

\displaystyle 3

\displaystyle 12

\displaystyle 21

\displaystyle 9

\displaystyle 7

Correct answer:

\displaystyle 3

Explanation:

\displaystyle \frac{x*7 +5*4+1}{y*2+4}= \frac{7x +21}{2y +4}=3

 

Multiply both sides by the denominator (2y +4) to cancel it:

\displaystyle \frac{7x +21}{2y +4}*(2y +4)=3*(2y+4)

\displaystyle 7x + 21=6y +12

Now, use substitution to solve for x:

\displaystyle \frac{x}{y}=\frac{12}{20}-->20x=12y-->10x=6y

Substitute 10x for 6y in the first equation:

\displaystyle 7x+21=(10x)+12

\displaystyle 9=3x

\displaystyle 3=x

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