Algebra II : Simplifying Expressions

Study concepts, example questions & explanations for Algebra II

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Example Questions

Example Question #141 : Variables

Simplify x(4 – x) – x(3 – x).

Possible Answers:

0

x

1

x2

3x

Correct answer:

x

Explanation:

You must multiply out the first set of parenthesis (distribute) and you get 4x – x2. Then multiply out the second set and you get –3x + x2. Combine like terms and you get x.

x(4 – x) – x(3 – x)

4x – x2 – x(3 – x)

4x – x2 – (3x – x2)

4x – x2 – 3x + x2 = x

Example Question #41 : Expressions

Divide:

\(\displaystyle \frac{3x^2+3x-6}{3x+6}\)

Possible Answers:

\(\displaystyle 3\)

\(\displaystyle x-1\)

\(\displaystyle x+2\)

\(\displaystyle -6\)

Correct answer:

\(\displaystyle x-1\)

Explanation:

Factor the numerator and denominator:

\(\displaystyle \frac{3x^2+3x-6}{3x+6}=\frac{3(x+2)(x-1)}{3(x+2)}\)

Cancel the factors that appear in both the numerator and the denominator:

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

Example Question #91 : Basic Single Variable Algebra

Simplify:        \(\displaystyle \frac{5p^{7}}{25p^{^{4}}}\)

Possible Answers:

\(\displaystyle \frac{p^{3}}{5}\)

\(\displaystyle \frac{p^{7/4}}{5}\)

\(\displaystyle \frac{p}{5}\)

\(\displaystyle 5p^{3}\)

\(\displaystyle \frac{p^{-3}}{5}\)

Correct answer:

\(\displaystyle \frac{p^{3}}{5}\)

Explanation:

\(\displaystyle p^{7}\) and \(\displaystyle p^{4}\) cancel out, leaving \(\displaystyle p^{3}\) in the numerator. 5 and 25 cancel out, leaving 5 in the denominator

Example Question #92 : Basic Single Variable Algebra

Simplify the following:

\(\displaystyle \frac{4x+6x^2}{2x}\)

Possible Answers:

\(\displaystyle 2x(2-3x)\)

\(\displaystyle \frac{2-3x}{2x}\)

\(\displaystyle \frac{2}{2x}-\frac{3}{2}\)

\(\displaystyle 2+3x\)

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

Correct answer:

\(\displaystyle 2+3x\)

Explanation:

\(\displaystyle \frac{4x+6x^2}{2x}\)

First, let us factor the numerator:

\(\displaystyle 4x+6x^2=x(4+6x)=2x(2+3x)\)

\(\displaystyle \frac{2x(2+3x)}{2x}=2+3x\)

Example Question #1 : Simplifying Expressions

Find the product:

\(\displaystyle \small 7n(8n-2)\)

Possible Answers:

\(\displaystyle \small n^2+14\)

\(\displaystyle \small 56n^2-14n\)

\(\displaystyle \small n-14\)

\(\displaystyle \small n^2-14n\)

Correct answer:

\(\displaystyle \small 56n^2-14n\)

Explanation:

First, mulitply the mononomial by the first term of the polynomial:

\(\displaystyle \small 7n\times8n\ = 56n^2\)

Second, multiply the monomial by the second term of the polynomial:

\(\displaystyle \small 7n\times (-2)\ = -14n\)

Add the terms together:

\(\displaystyle \small 56n^2\ +\ (-14n)\ = 56n^2-14n\)

Example Question #11 : How To Multiply Monomial Quotients

Multiply, expressing the product in simplest form:

\(\displaystyle \small \frac{15x^{5}}{14y^{3}} \cdot \frac{21y^{2} }{25x^{3}}\)

Possible Answers:

\(\displaystyle \small \small \small \small \small \frac{10 y}{9x^{2} }\)

\(\displaystyle \small \small \frac{9 x^{2}}{10 y}\)

\(\displaystyle \small \small \small \small \frac{10 x^{2}}{9y }\)

\(\displaystyle \small \small \small \frac{9 x^{2}y}{10 }\)

\(\displaystyle \small \small \small \small \frac{9 y}{10x^{2} }\)

Correct answer:

\(\displaystyle \small \small \frac{9 x^{2}}{10 y}\)

Explanation:

Cross-cancel the coefficients by dividing both 15 and 25 by 5, and both 14 and 21 by 7:

\(\displaystyle \small \small \small \small \frac{15x^{5}}{14y^{3}} \cdot \frac{21y^{2} }{25x^{3}} = \small \small \small \small \frac{3x^{5}}{2y^{3}} \cdot \frac{3y^{2} }{5x^{3}} = \frac{3x^{5} \cdot 3y^{2}}{5x^{3} \cdot 2y^{3}} = \frac{3 \cdot 3 \cdot x^{5} y^{2}}{5\cdot 2\cdot x^{3} y^{3}} = \frac{9 x^{5} y^{2}}{10 x^{3} y^{3}}\) 

Now use the quotient rule on the variables by subtracting exponents:

\(\displaystyle \small \frac{9 x^{5} y^{2}}{10 x^{3} y^{3}} = \frac{9 x^{5-3}}{10 y^{3-2}} = \frac{9 x^{2}}{10 y^{1}} = \frac{9 x^{2}}{10 y}\)

Example Question #11 : How To Multiply Monomial Quotients

Simplify the following:

\(\displaystyle \frac{2xy^2}{3yz^2} \times \frac{15y^2z}{14x^2y}\)

Possible Answers:

\(\displaystyle \frac{5xz}{7y^2}\)

\(\displaystyle \frac{5y^2}{7xz}\)

\(\displaystyle \frac{5xy^2}{7z}\)

\(\displaystyle \frac{7y^2}{5x^2z}\)

Correct answer:

\(\displaystyle \frac{5y^2}{7xz}\)

Explanation:

In this problem, you have two fractions being multiplied. You can first simplify the coefficients in the numerators and denominators. You can divide and cancel the 2 and 14 each by 2, and the 3 and 15 each by 3:

\(\displaystyle \frac{2xy^2}{3yz^2} \times \frac{15y^2z}{14x^2y} = \frac{xy^2}{yz^2} \times \frac{5y^2z}{7x^2y}\)

You can multiply the two numerators and two denominators, keeping in mind that when multiplying like variables with exponents, you simplify by adding the exponents together:

\(\displaystyle \frac{xy^2}{yz^2} \times \frac{5y^2z}{7x^2y} = \frac{5xy^4z}{7x^2y^2z^2}\)

Any variables that are both in the numerator and denominator can be simplified by subtracting the numerator's exponent by the denominator's exponent. If you end up with a negative exponent in the numerator, you can move the variable to the denominator to keep the exponent positive:

\(\displaystyle \frac{5xy^4z}{7x^2y^2z^2} = \frac{5y^2}{7xz}\)

Example Question #91 : Factoring Polynomials

Factor the expression:

\(\displaystyle \small \small 2xy^3-14xy^2+9xy\)

Possible Answers:

\(\displaystyle \small xy(2y^2-14y+9)\)

\(\displaystyle \small xy^3(2-14xy^2+9xy)\)

\(\displaystyle \small 2xy^3(-14xy^2+9xy)\)

\(\displaystyle \small 2xy(y^2-7xy+9)\)

\(\displaystyle \small x(2y^3-14y^2+9y)\)

Correct answer:

\(\displaystyle \small xy(2y^2-14y+9)\)

Explanation:

To find the greatest common factor, we need to break each term into its prime factors:

\(\displaystyle \small 2xy^3=2 \cdot x \cdot y \cdot y \cdot y\)

\(\displaystyle \small 14xy^2 = 2 \cdot 7 \cdot x \cdot y \cdot y\)

\(\displaystyle \small 9xy = 3 \cdot 3 \cdot x \cdot y\)

Looking at which terms all three expressions have in common; thus, the GCF is \(\displaystyle \small xy\). We then factor this out: \(\displaystyle \small \small xy(2y^2 -14y +9)\)

Example Question #1 : Monomials

Expand: \(\displaystyle 8x(3x+7)\)

 

Possible Answers:

\(\displaystyle 24x^2 + 56\)

\(\displaystyle 24x^2 + 56x\)

\(\displaystyle 11x + 15\)

\(\displaystyle 11x^2 + 15x\)

\(\displaystyle 24x + 56\)

Correct answer:

\(\displaystyle 24x^2 + 56x\)

Explanation:

To expand, multiply 8x by both terms in the expression (3x + 7).

8x multiplied by 3x is 24x².

8x multiplied by 7 is 56x.

Therefore, 8x(3x + 7) = 24x² + 56x.

Example Question #1 : Simplifying Expressions

Simplify:

\(\displaystyle -5(x+15)-3x\)

Possible Answers:

\(\displaystyle 2x+15\)

\(\displaystyle 2x-75\)

\(\displaystyle -8x-75\)

\(\displaystyle -8x+15\)

None of the other answers are correct.

Correct answer:

\(\displaystyle -8x-75\)

Explanation:

First, distribute –5 through the parentheses by multiplying both terms by –5.

\(\displaystyle -5(x+15)-3x=-5x-75-3x\)

Then, combine the like-termed variables (–5x and –3x).

\(\displaystyle -5x-75-3x=-8x-75\)

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