Algebra II : Simplifying Expressions

Study concepts, example questions & explanations for Algebra II

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Example Questions

Example Question #1 : Binomials

Expand:

\(\displaystyle \frac{1}{3}(2x^2-6)(4x-\frac{2}{3})\)

Possible Answers:

\(\displaystyle 2\frac{2}{3}x^3-\frac{4}{9}x^2+8x+1\frac{1}{3}\)

\(\displaystyle -2\frac{2}{3}x^3-\frac{4}{9}x^2-8x+1\frac{1}{3}\)

\(\displaystyle 2\frac{2}{3}x^3+\frac{4}{9}x^2-8x+1\frac{1}{3}\)

\(\displaystyle 2\frac{2}{3}x^3-\frac{4}{9}x^2-8x+1\frac{1}{3}\)

\(\displaystyle 2\frac{2}{3}x^3-\frac{4}{9}x^2-8x-1\frac{1}{3}\)

Correct answer:

\(\displaystyle 2\frac{2}{3}x^3-\frac{4}{9}x^2-8x+1\frac{1}{3}\)

Explanation:

First, FOIL:

\(\displaystyle \frac{1}{3}(8x^3-\frac{4}{3}x^2-24x+\frac{12}{3})\)

Simplify:

\(\displaystyle \frac{1}{3}(8x^3-\frac{4}{3}x^2-24x+4)\)

Distribute the \(\displaystyle \frac{1}{3}\) through the parentheses:

\(\displaystyle \frac{8}{3}x^3-\frac{4}{9}x^2-\frac{24}{3}x+\frac{4}{3}\)

Rewrite to make the expression look like one of the answer choices:

\(\displaystyle 2\frac{2}{3}x^3-\frac{4}{9}x^2-8x+1\frac{1}{3}\)

Example Question #1 : How To Add Polynomials

Simplify the expression.

\(\displaystyle 15x^{3}y^{2}+8x^{2}+3x^{3}y^{2}-4x^{2}\)

Possible Answers:

\(\displaystyle 18x^{3}y^{2}+4x^{2}\)

\(\displaystyle 22x^{6}y^{4}\)

\(\displaystyle 22x^3y^{2}x^{2}\)

None of the other answers are correct.

\(\displaystyle 18x^{3}y^{2}-4x^{2}\)

Correct answer:

\(\displaystyle 18x^{3}y^{2}+4x^{2}\)

Explanation:

When simplifying polynomials, only combine the variables with like terms.

\(\displaystyle 15x^{3}y^{2}\) can be added to \(\displaystyle 3x^{3}y^{2}\), giving \(\displaystyle 18x^{3}y^{2}\)

\(\displaystyle 4x^{2}\) can be subtracted from \(\displaystyle 8x^{2}\) to give \(\displaystyle 4x^{2}\).

Combine both of the terms into one expression to find the answer: \(\displaystyle 18x^{3}y^{2}+4x^{2}\)

Example Question #2 : How To Add Polynomials

Simplify the following expression.

\(\displaystyle (5c^{2}+5)+(-5c-5)\)

Possible Answers:

\(\displaystyle 5c^{2}-5c+10\)

\(\displaystyle -10\)

\(\displaystyle 5c^{2}-5c-25\)

\(\displaystyle 0\)

\(\displaystyle 5c^{2}-5c\)

Correct answer:

\(\displaystyle 5c^{2}-5c\)

Explanation:

\(\displaystyle (5c^{2}+5)+(-5c-5)\)

This is not a FOIL problem, as we are adding rather than multiplying the terms in parentheses.

Add like terms to solve.

\(\displaystyle 5c^{2}\) and \(\displaystyle -5c\) have no like terms and cannot be combined with anything.

5 and -5 can be combined however:

\(\displaystyle 5-5=0\)

This leaves us with \(\displaystyle 5c^{2}-5c\).

Example Question #2 : How To Subtract Polynomials

Simplify the following:

\(\displaystyle 4x^3-2x(x-2)(x+3)\)

Possible Answers:

None of the other answers are correct.

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

\(\displaystyle 4x^3-2x^3-2x^2+12x\)

\(\displaystyle 2x^3-2x^2+12x\)

\(\displaystyle 8x^3-2x+16\)

Correct answer:

\(\displaystyle 2x^3-2x^2+12x\)

Explanation:

\(\displaystyle 4x^3-2x(x-2)(x+3)\)

First, FOIL the two binomials:

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

Then distribute the \(\displaystyle 2x\) through the terms in parentheses:

\(\displaystyle 4x^3-2x^3-2x^2+12x\)

Combine like terms:

\(\displaystyle 2x^3-2x^2+12x\)

Example Question #1 : How To Subtract Polynomials

Simplify the following expression:

\(\displaystyle (2q^{2}+4q+7)-(3q^{2}-5)\)

Possible Answers:

\(\displaystyle -5q^{2}+4q+2\)

\(\displaystyle -q^2+4q+2\)

\(\displaystyle -3q^{2}+12\)

\(\displaystyle -q^{2}+4q+12\)

Correct answer:

\(\displaystyle -q^{2}+4q+12\)

Explanation:

This is not a FOIL problem, as we are adding rather than multiplying the terms in parentheses.

Add like terms together:

\(\displaystyle 2q^{2}-3q^{2}=-1q^{2}=-q^2\)

\(\displaystyle 4q\) has no like terms.

\(\displaystyle 7-(-5)=12\)

Combine these terms into one expression to find the answer:

\(\displaystyle -q^{2}+4q+12\)

Example Question #91 : Variables

Simplify the expression.

\(\displaystyle x^{5}*x^{16}\)

Possible Answers:

\(\displaystyle x^{11}\)

\(\displaystyle 2x^{16}\)

The expression cannot be simplified further.

\(\displaystyle x^{21}\)

\(\displaystyle x^{80}\)

Correct answer:

\(\displaystyle x^{21}\)

Explanation:

When multiplying exponential components, you must add the powers of each term together.

\(\displaystyle 5+16=21\)

\(\displaystyle x^{5}*x^{16}=x^{21}\)

Example Question #92 : Variables

\(\displaystyle x^{5}y^{17}*x^{2}y^{2}=?\)

Possible Answers:

\(\displaystyle 2x^{2}x^{7}y^{19}\)

\(\displaystyle x^{2}y^{8}\)

\(\displaystyle x^{7}y^{19}\)

None of the other answers are correct.

\(\displaystyle x^{10}y^{34}\)

Correct answer:

\(\displaystyle x^{7}y^{19}\)

Explanation:

When multiplying polynomials, add the powers of each like-termed variable together.

For x: 5 + 2 = 7

For y: 17 + 2 = 19

Therefore the answer is \(\displaystyle x^{7}y^{19}\) .

Example Question #11 : Simplifying Expressions

Simplify the following:

\(\displaystyle \frac{x^2-10x+25}{x^2-25}\)

Possible Answers:

\(\displaystyle 0\)

This fraction cannot be simplified.

\(\displaystyle \frac{(x-5)(x-5)}{(x-5)(x+5)}\)

\(\displaystyle \frac{x-5}{x+5}\)

\(\displaystyle 1\)

Correct answer:

\(\displaystyle \frac{x-5}{x+5}\)

Explanation:

\(\displaystyle \frac{x^2-10x+25}{x^2-25}\)

First we will factor the numerator:

\(\displaystyle x^2-10x+25=(x-5)(x-5)\)

Then factor the denominator:

\(\displaystyle x^2-25=(x+5)(x-5)\)

We can re-write the original fraction with these factors and then cancel an (x-5) term from both parts:

\(\displaystyle \frac{(x-5)(x-5)}{(x-5)(x+5)}=\frac{x-5}{x+5}\)

Example Question #1 : Operations With Polynomials

Divide \(\displaystyle 3x^3+5x^2-x+8\) by \(\displaystyle x^2-1\).

 

Possible Answers:

\(\displaystyle 3x+5+\frac{2x+13}{x^2-1}\)

\(\displaystyle x^2-1-\frac{3x+5}{2x+13}\)

\(\displaystyle 3x+5+\frac{x^2+1}{2x-13}\)

\(\displaystyle 2x+13+\frac{3x+5}{x^2-1}\)

\(\displaystyle 3x+5-\frac{2x+13}{x^2-1}\)

Correct answer:

\(\displaystyle 3x+5+\frac{2x+13}{x^2-1}\)

Explanation:

First, set up the division as the following:

\(\displaystyle \begin{array}{*2r @{\hskip\arraycolsep}c@{\hskip\arraycolsep} *4r} & && & & & \\ \cline{3-7} x^2 & -1 &\big)& 3x^3 & 5x^2 & -x & 8 \end{array}\)

Look at the leading term \(\displaystyle x^2\) in the divisor and \(\displaystyle 3x^3\) in the dividend. Divide \(\displaystyle 3x^3\) by \(\displaystyle x^2\) gives \(\displaystyle 3x\); therefore, put \(\displaystyle 3x\) on the top:

\(\displaystyle \begin{array}{*2r @{\hskip\arraycolsep}c@{\hskip\arraycolsep} *4r} & && 3x & & & \\ \cline{3-7} x^2 & -1 &\big)& 3x^3 & 5x^2 & -x & 8 \end{array}\)

Then take that \(\displaystyle 3x\) and multiply it by the divisor, \(\displaystyle x^2-1\), to get \(\displaystyle 3x^3-3x\).  Place that \(\displaystyle 3x^3-3x\) under the division sign:

\(\displaystyle \begin{array}{*2r @{\hskip\arraycolsep}c@{\hskip\arraycolsep} *4r} & && 3x & & & \\ \cline{3-7} x^2 & -1 &\big)& 3x^3 & 5x^2 & -x & 8 \\ & && 3x^3 & -3x \end{array}\)

Subtract the dividend by that same \(\displaystyle 3x^3-3x\) and place the result at the bottom. The new result is \(\displaystyle 5x^2+2x+8\), which is the new dividend.

\(\displaystyle \begin{array}{*2r @{\hskip\arraycolsep}c@{\hskip\arraycolsep} *4r} & && 3x & & & \\ \cline{3-7} x^2 & -1 &\big)& 3x^3 & 5x^2 & -x & 8 \\ & && 3x^3 & -3x \\ \cline{4-7} & && & 5x^2 & 2x & 8 \end{array}\)

Now, \(\displaystyle 5x^2\) is the new leading term of the dividend.  Dividing \(\displaystyle 5x^2\) by \(\displaystyle x^2\) gives 5.  Therefore, put 5 on top:

\(\displaystyle \begin{array}{*2r @{\hskip\arraycolsep}c@{\hskip\arraycolsep} *4r} & && 3x & 5 & & \\ \cline{3-7} x^2 & -1 &\big)& 3x^3 & 5x^2 & -x & 8 \\ & && 3x^3 & -3x \\ \cline{4-7} & && & 5x^2 & 2x & 8 \end{array}\)

Multiply that 5 by the divisor and place the result, \(\displaystyle 5x^2-5\), at the bottom:

\(\displaystyle \begin{array}{*2r @{\hskip\arraycolsep}c@{\hskip\arraycolsep} *4r} & && 3x & 5 & & \\ \cline{3-7} x^2 & -1 &\big)& 3x^3 & 5x^2 & -x & 8 \\ & && 3x^3 & -3x \\ \cline{4-7} & && & 5x^2 & 2x & 8 \\ & && & 5x^2 & -5 \end{array}\)

Perform the usual subtraction:

\(\displaystyle \begin{array}{*2r @{\hskip\arraycolsep}c@{\hskip\arraycolsep} *4r} & && 3x & 5 & & \\ \cline{3-7} x^2 & -1 &\big)& 3x^3 & 5x^2 & -x & 8 \\ & && 3x^3 & -3x \\ \cline{4-7} & && & 5x^2 & 2x & 8 \\ & && & 5x^2 & -5 \\ \cline{5-7} & && & & 2x & 13 \\ \end{array}\)

Therefore the answer is \(\displaystyle 3x+5\) with a remainder of \(\displaystyle 2x+13\), or \(\displaystyle 3x+5+\frac{2x+13}{x^2-1}\).

Example Question #111 : Basic Single Variable Algebra

Simplify the expression:

\(\displaystyle \frac{x^{2}y^{15}z^{-2}}{x^{5}y^{4}}\)

Possible Answers:

\(\displaystyle \frac{y^{12}}{x^{2}z^{2}}\)

\(\displaystyle \frac{y^{9}}{z^{2}}\)

The fraction cannot be simplified further.

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

\(\displaystyle \frac{y^{11}}{x^{3}z^{2}}\)

Correct answer:

\(\displaystyle \frac{y^{11}}{x^{3}z^{2}}\)

Explanation:

When dividing polynomials, subtract the exponent of the variable in the numberator by the exponent of the same variable in the denominator.

If the power is negative, move the variable to the denominator instead.

First move the negative power in the numerator to the denominator:

\(\displaystyle \frac{x^{2}y^{15}}{x^{5}y^{4}z^{2}}\)

Then subtract the powers of the like variables:

\(\displaystyle \frac{y^{11}}{x^{3}z^{2}}\)

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