ISEE Upper Level Math : Exponential Operations

Study concepts, example questions & explanations for ISEE Upper Level Math

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Example Questions

Example Question #102 : Numbers And Operations

Simplify the following expression:

\(\displaystyle \frac{16r^{19}}{8r^6}\)

Possible Answers:

\(\displaystyle 2r^5\)

\(\displaystyle 2r^{13}\)

\(\displaystyle 2r^{\frac{19}{6}}\)

\(\displaystyle 8r^{13}\)

Correct answer:

\(\displaystyle 2r^{13}\)

Explanation:

Simplify the following expression:

\(\displaystyle \frac{16r^{19}}{8r^6}\)

To solve this question, we need to recall that when dividing exponents we subtract them.

When dividing coefficients, we treat them as regular division.

In this case, we can break up our question into two parts:

\(\displaystyle \frac{16r^{19}}{8r^6}\rightarrow\frac{16}{8} \frac{r^{19}}{r^6}\)

The coefficients will simply reduce to "2", because 16 divided by 8 is two

The r's are another story. We subtract, so we will get the following:

\(\displaystyle \frac{r^{19}}{r^6}=r^{19-6}=r^{13}\)

So, if we put our two parts back together, we get:

\(\displaystyle 2r^{13}\)

Example Question #103 : Numbers And Operations

Simplify the following:

\(\displaystyle \frac{18t^6u^{14}}{6t^3u^{12}}\)

Possible Answers:

\(\displaystyle 3t^3u^2\)

\(\displaystyle 3t^2u^2\)

\(\displaystyle 12t^3u^2\)

\(\displaystyle 3t^3u^3\)

Correct answer:

\(\displaystyle 3t^3u^2\)

Explanation:

Simplify the following:

\(\displaystyle \frac{18t^6u^{14}}{6t^3u^{12}}\)

Let's begin by recalling that when dividing variables with similar base, we need to subtract the exponents.

To deal with the coefficients, simply treat them as a fraction and simplify.

\(\displaystyle \frac{18t^6u^{14}}{6t^3u^{12}}=\frac{18}{6}t^{6-3}u^{14-12}=3t^3u^2\)

So our answer is

\(\displaystyle 3t^3u^2\)

Example Question #51 : Exponential Operations

Simplify the expression: 

\(\displaystyle 6x^{4} + 8x^{3} - 4x^{2}\)

Possible Answers:

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

\(\displaystyle 6x^{4} + 4x^{5}\)

\(\displaystyle 10x^{9}\)

\(\displaystyle 10x^{5}\)

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

Correct answer:

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

Explanation:

\(\displaystyle 6x^{4} + 8x^{3} - 4x^{2}\)

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

Example Question #52 : Exponential Operations

Simplify:

 

\(\displaystyle 4x^2+8x^3+16x^2+4x^3\)

Possible Answers:

\(\displaystyle 4x(5+3x)\)

\(\displaystyle 4x^2(5+3x^2)\)

\(\displaystyle x^2(5+3x)\)

\(\displaystyle 4x^2(5+3x)\)

\(\displaystyle 4x^2(5+x)\)

Correct answer:

\(\displaystyle 4x^2(5+3x)\)

Explanation:

In order to add exponential terms, both the base and the exponent must be the same. So we can write:

 

\(\displaystyle 4x^2+8x^3+16x^2+4x^3=(4x^2+16x^2)+(8x^3+4x^3)\)

\(\displaystyle =20x^2+12x^3=4x^2(5+3x)\)

Example Question #55 : Exponents

Evaluate:

 

\(\displaystyle \frac{x^0+y^0+1}{x^0-y^0-1}\)

Possible Answers:

\(\displaystyle 1\)

\(\displaystyle 3\)

\(\displaystyle -3\)

\(\displaystyle 0\)

\(\displaystyle 2\)

Correct answer:

\(\displaystyle -3\)

Explanation:

Based on the zero-exponent rule we have:

 

\(\displaystyle a^0=1\)

 

That means any non-zero number raised to the zero power is equal to \(\displaystyle 1\). So we can write:

 

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

 

 

Example Question #3 : How To Add Exponents

What is the value of the expression:

\(\displaystyle x^{3}\cdotx^{y}\cdot x^{2+y}\)

Possible Answers:

\(\displaystyle x^{4}\cdotx^{y+4}\)

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

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

\(\displaystyle x^{6}\cdotx^{y+2}\)

Correct answer:

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

Explanation:

When values, having the same base, are multiplied by one another, the exponents are added together and the base stays the same. 

Thus, 

\(\displaystyle x^{3}\cdotx^{y}\cdot x^{2+y}\)

is equal to 

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

Example Question #4 : How To Add Exponents

Simplify: \(\displaystyle x^{7}\cdot2x^{3}\)

Possible Answers:

\(\displaystyle x^{21}\)

\(\displaystyle x^{10}\)

\(\displaystyle 2x^{10}\)

\(\displaystyle 2x^{21}\)

Correct answer:

\(\displaystyle 2x^{10}\)

Explanation:

When multiplying exponents, the exponents are added together. Thus, 3 and 7 are added together for a sum of 10. In this problem, the "2" becomes a coefficient in front of the x. Therefore, the correct answer is:

\(\displaystyle 2x^{10}\)

Example Question #5 : How To Add Exponents

Simplify:

\(\displaystyle x^{6}\cdot x^{4}\)

Possible Answers:

\(\displaystyle x^{2}\)

\(\displaystyle x^{24}\)

\(\displaystyle x^{10}\)

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

\(\displaystyle x^{-10}\)

Correct answer:

\(\displaystyle x^{10}\)

Explanation:

When multiplying exponents, the exponents are added together.

\(\displaystyle x^{6}\cdot x^{4} = x^{6+4}=x^{10}\)

Example Question #6 : How To Add Exponents

Simplify:

\(\displaystyle 2x^{2}\cdot 3x^{4}\)

Possible Answers:

\(\displaystyle 5x^{6}\)

\(\displaystyle 6x^{6}\)

\(\displaystyle 6x^{8}\)

\(\displaystyle 6x^{2}\)

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

Correct answer:

\(\displaystyle 6x^{6}\)

Explanation:

When multiplying exponents, the exponents are added together.

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

Example Question #60 : Exponents

Simplify the expression:

\(\displaystyle 3x^{4}+6x^{3}-9x^{2}\)

Possible Answers:

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

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

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

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

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

Correct answer:

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

Explanation:

To simplify this problem we need to factor out a \(\displaystyle 3x^2\)

\(\displaystyle 3x^{4}+6x^{3}-9x^{2}\)

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

 

We can do this because multiplying exponents is the same as adding them. Therefore,

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

\(\displaystyle =3x^2 \cdot x^2 +3x^2\cdot2x -3x^2\cdot3=3x^{2+2}+3\cdot2x^{2+1}-3\cdot 3x^2\)

\(\displaystyle =3x^4+6x^3-9x^2\)

 

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