Algebra II : Addition and Subtraction

Study concepts, example questions & explanations for Algebra II

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Example Questions

Example Question #1 : Addition And Subtraction

Menu

Above is the menu at a coffee shop.

Jerry has a coupon that entitles him to a free butter croissant with the purchase of one large drink of any kind. The coupon says "limit one per coupon".

He decides to purchase a large espresso, a large cappucino, and two butter croissants. Disregarding tax, how much will he pay for them?

Possible Answers:

\(\displaystyle \$7.18\)

\(\displaystyle \$14.04\)

\(\displaystyle \$11.56\)

None of the other responses is correct.

\(\displaystyle \$9.47\)

Correct answer:

\(\displaystyle \$9.47\)

Explanation:

The coupon will entitle him to one free croissant, so Jerry will pay for the large espresso, the large cappucino, and one butter croissant. The charge will be the sum of the three prices:

\(\displaystyle \begin{matrix} \$3.29 \\ \; \; 3.89\\ \underline{+2.29} \\ \$9.47 \end{matrix}\)

Example Question #1 : Elementary Operations

Find the distance, \(\displaystyle d\), between point \(\displaystyle A\) and point \(\displaystyle B\).

\(\displaystyle A = (3, 4) B = (2, 5)\)

Possible Answers:

\(\displaystyle -1.41\)

\(\displaystyle 1.41\)

\(\displaystyle 1.14\)

\(\displaystyle 1.40\)

\(\displaystyle 1.42\)

Correct answer:

\(\displaystyle 1.41\)

Explanation:

Use the distance formula to solve this problem.

\(\displaystyle A=(x_1,y_1), B=(x_2,y_2)\)

\(\displaystyle d=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}\)

Plugging in our points A and B we get the following distance.

\(\displaystyle A = (3, 4) B = (2, 5)\)

\(\displaystyle d = \sqrt{(2 - 3)^{2} + (5 - 4)^{2}}\)

\(\displaystyle d = \sqrt{1 + 1} = \sqrt{2} = 1.41\)

Example Question #2 : Elementary Operations

Solve the equation by Substitution.

\(\displaystyle 2x + 4y = 10\)

\(\displaystyle 5x - 3y = 11\)

Possible Answers:

\(\displaystyle (2, 1)\)

\(\displaystyle (0, 2)\)

\(\displaystyle (-2.85, -1.08)\)

\(\displaystyle (2.85, 1.08)\)

\(\displaystyle (1, 0)\)

Correct answer:

\(\displaystyle (2.85, 1.08)\)

Explanation:

First, take the first equation and solve for x in terms of y.

\(\displaystyle 2x + 4y = 10\)

\(\displaystyle -4y -4y\)

\(\displaystyle 2x = -4y + 10\)

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

From here, substitute the equation you found for x into the second equation and solve for y. 

\(\displaystyle 5x - 3y = 11\)

\(\displaystyle 5 (-2y + 5) - 3y = 11\)

\(\displaystyle -10y + 25 - 3y = 11\)

\(\displaystyle -13y + 25 = 11\)

\(\displaystyle -25 -25\)

\(\displaystyle -13y = -14\)

\(\displaystyle y = 1.08\)

Now, substitute the y value found into the original equation and solve for x.

\(\displaystyle 2x + 4y = 10\)

\(\displaystyle 2x + 4(1.08) = 10\)

\(\displaystyle 2x + 4.32 = 10\)

\(\displaystyle -4.32 -4.32\)

\(\displaystyle 2x = 5.68\)

\(\displaystyle x = 2.85\)

 

 

Example Question #2 : Addition And Subtraction

Solve the equation by Elimination.

\(\displaystyle 5x - y = 7\)

\(\displaystyle 6x - 2y = 6\)

Possible Answers:

\(\displaystyle (3, 3)\)

\(\displaystyle (2, 3)\)

\(\displaystyle (-1, 2)\)

\(\displaystyle (2, -3)\)

\(\displaystyle (3, 2)\)

Correct answer:

\(\displaystyle (2, 3)\)

Explanation:

To solve this system of equations by elimination you first need to multiply the first equation by -2. This will allow the y terms to cancel when equation 1 and equation 2 are adding together.

\(\displaystyle -2 \times \left \{ 5x - y = 7 \right \} = -10x + 2y = -14\)

\(\displaystyle \left \{ 6x - 2y = 6 \right \} = 6x - 2y = 6\)

Now solve for x.

\(\displaystyle -4x = -8\)

\(\displaystyle x = 2\)

Substitute the x value into the orginial equation and solve for y.

\(\displaystyle 5x - y = 7\)

\(\displaystyle 5(2) - y = 7\)

\(\displaystyle 10 - y = 7\)

\(\displaystyle -10 -10\)

\(\displaystyle -y = -3\)

\(\displaystyle y = 3\) 

Example Question #4 : How To Subtract Polynomials

Subtract:

\(\displaystyle \left (\frac{3}{4}x + \frac{2}{5} \right ) - \left (\frac{1}{8}x - \frac{1}{10} \right )\)

Possible Answers:

\(\displaystyle \frac{5}{8}x + \frac{1}{2}\)

\(\displaystyle \frac{5}{8}x - \frac{3}{10}\)

\(\displaystyle \frac{5}{8}x + \frac{1}{15}\)

\(\displaystyle \frac{5}{8}x - \frac{1}{2}\)

\(\displaystyle \frac{5}{8}x + \frac{3}{10}\)

Correct answer:

\(\displaystyle \frac{5}{8}x + \frac{1}{2}\)

Explanation:

\(\displaystyle \left (\frac{3}{4}x + \frac{2}{5} \right ) - \left (\frac{1}{8}x - \frac{1}{10} \right )\)

\(\displaystyle =\frac{3}{4}x + \frac{2}{5} - \frac{1}{8}x + \frac{1}{10}\)

\(\displaystyle =\frac{3}{4}x- \frac{1}{8}x + \frac{2}{5} + \frac{1}{10}\)

\(\displaystyle =\frac{6}{8}x- \frac{1}{8}x + \frac{4}{10} + \frac{1}{10}\)

\(\displaystyle =\frac{5}{8}x + \frac{5}{10}\)

\(\displaystyle =\frac{5}{8}x + \frac{1}{2}\)

Example Question #5 : Addition And Subtraction

Simplify, if possible:   \(\displaystyle -3a^2bc+3ab^2-4a^2b+2a^2bc\)

Possible Answers:

\(\displaystyle -a^2bc+3ab^2-4a^2b\)

\(\displaystyle -5a^2bc-a^2b\)

\(\displaystyle -a^2bc-a^2b\)

\(\displaystyle -5a^2bc+3ab^2\)

\(\displaystyle -a^2bc-a^2b^2\)

Correct answer:

\(\displaystyle -a^2bc+3ab^2-4a^2b\)

Explanation:

There is only one like-term in the expression given, which is \(\displaystyle a^2bc\).

\(\displaystyle -3a^2bc+3ab^2-4a^2b+2a^2bc\)

Add the like term.  The rest of the terms cannot be combined by adding or subtracting.

The correct answer is:

\(\displaystyle -a^2bc+3ab^2-4a^2b\)

Example Question #4871 : Algebra Ii

Solve:  \(\displaystyle -7xy + 8y- 2x(y+3)+6(y-3)\)

Possible Answers:

\(\displaystyle -19xy-18\)

\(\displaystyle -5xy + 14y-6x-18\)

\(\displaystyle -9xy + 14y-6x-18\)

\(\displaystyle -9xy + 6y-6x-18\)

\(\displaystyle -9xy + 8y-18\)

Correct answer:

\(\displaystyle -9xy + 14y-6x-18\)

Explanation:

Simplify first by eliminating the parentheses. To do this you will need to distribute the coefficient term outside the parentheses to each term within the parentheses. 

\(\displaystyle -7xy + 8y- 2x(y+3)+6(y-3)\)

Next, combine like terms.

\(\displaystyle =-7xy + 8y- 2xy-6x+6y-18\)

\(\displaystyle =-9xy + 14y-6x-18\)

Example Question #7 : Addition And Subtraction

Solve:  \(\displaystyle 2369+32\)

Possible Answers:

\(\displaystyle 2411\)

\(\displaystyle 2701\)

\(\displaystyle 5569\)

\(\displaystyle 2391\)

\(\displaystyle 2401\) 

Correct answer:

\(\displaystyle 2401\) 

Explanation:

Add the ones digits.

\(\displaystyle 9+2 = 11\)

Since this number is \(\displaystyle 10\) or greater, use the tens digit as a carry over.

Add the tens digits with the carry over.

\(\displaystyle 6+3+(1)=10\)

Add the hundreds digit with the carry over.  The hundreds digit for the second number in the problem is zero.

\(\displaystyle 3+0+(1)= 4\)

Since there is no carry over and there is no thousands digit for the second number, the thousands digit of the answer is just \(\displaystyle 2\).

Combine all the ones digits in chronological order from thousands to the ones digits.

The answer is:  \(\displaystyle 2401\)

Example Question #8 : Addition And Subtraction

Solve:  \(\displaystyle 2a-ab^2+3ab+4ab^2+9a+6ab\)

Possible Answers:

\(\displaystyle 11a-3ab^2+9ab\)

\(\displaystyle -7a-3ab^2+5ab\)

\(\displaystyle -7a+3ab^2+9ab\)

\(\displaystyle 11a+3ab^2+9ab\)

\(\displaystyle -7a-3ab^2+9ab\)

Correct answer:

\(\displaystyle 11a+3ab^2+9ab\)

Explanation:

In order to simplify this, we need to combine like-terms.  The coefficients of unlike terms cannot be combined.

Add \(\displaystyle 2a\) and \(\displaystyle 9a\).

\(\displaystyle 2a+9a = 11a\)

Add \(\displaystyle -ab^2\) and \(\displaystyle 4ab^2\).

\(\displaystyle -ab^2+4ab^2 = 3ab^2\)

Add \(\displaystyle 3ab\) and \(\displaystyle 6ab\).

\(\displaystyle 3ab+ 6ab =9ab\)

Combine all the terms.

The answer is:  \(\displaystyle 11a+3ab^2+9ab\)

Example Question #9 : Addition And Subtraction

Solve:  \(\displaystyle 61 - 1 4 + 23\)

Possible Answers:

\(\displaystyle 75\)

\(\displaystyle 70\)

\(\displaystyle 78\)

\(\displaystyle -38\)

\(\displaystyle 60\)

Correct answer:

\(\displaystyle 70\)

Explanation:

In order to solve the problem, first evaluate \(\displaystyle 61-1 4\).

Borrow a one from the six in the tens digit in order to subtract the ones digit.

\(\displaystyle 11-4 = 7\)

The six in the tens digit becomes a five.  Subtract the five with the tens digit of the second number.

\(\displaystyle 5-1 =4\)

\(\displaystyle 61-1 4 = 47\)

Add \(\displaystyle 47 +23\).

Add the ones digit. 

\(\displaystyle 7+3 = 10\)

Since the number is ten or greater, use the tens digit as a carryover to the next calculation.

\(\displaystyle 4+2+(1) = 7\)

Combine the ones digits.

The answer is \(\displaystyle 70\).

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