SSAT Upper Level Math : Properties of Exponents

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

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Example Questions

Example Question #561 : Grade 6

What is \(\displaystyle 23\times23\times23\times23\times23\times23\) in exponential notation? 

Possible Answers:

\(\displaystyle 23\times6\)

\(\displaystyle 6\times6\times6\times6\times6\times6\times6\times6\times6\times6\times6\)

\(\displaystyle 6\times23\)

\(\displaystyle 6^{23}\)

\(\displaystyle 23^6\)

Correct answer:

\(\displaystyle 23^6\)

Explanation:

Exponential notation includes a base number and an exponent. The base number is the number that is being multiplied and the exponent is how many times the base number is being multiplied to itself.

In this case, \(\displaystyle 23\) is our base number and it's being multiplied to itself \(\displaystyle 6\) times, so that is our exponent.  

Example Question #171 : Ssat Upper Level Quantitative (Math)

\(\displaystyle x^{5} = - 77\)

\(\displaystyle y = -2\)

\(\displaystyle (xy) ^{5} =?\)

Possible Answers:

\(\displaystyle -45\)

\(\displaystyle - 2,464\)

\(\displaystyle 2,464\)

\(\displaystyle -109\)

Correct answer:

\(\displaystyle 2,464\)

Explanation:

Apply the Power of a Product Principle:

\(\displaystyle (xy) ^{5} = x^{5} y ^{5}\)

Setting \(\displaystyle x^{5} = - 77\)  and \(\displaystyle y = -2\), keeping in mind that an odd power of a negative number is negative:

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

\(\displaystyle = -77 \cdot (-2 ) ^{5}\)

\(\displaystyle = -77 \cdot[ - (2 ^{5} )]\)

\(\displaystyle = -77 \cdot (-32)\)

\(\displaystyle = + (77 \cdot 32)\)

\(\displaystyle = 2,464\)

Example Question #123 : How To Find The Properties Of An Exponent

\(\displaystyle y > 0\) and \(\displaystyle z> 0\)

\(\displaystyle y^{2} = 12\)

\(\displaystyle z^{2} = 5\)

Evaluate \(\displaystyle (y z)^{3}\).

Possible Answers:

\(\displaystyle 12\sqrt{30}\)

\(\displaystyle 12\sqrt{15}\)

\(\displaystyle 120 \sqrt{30 }\)

\(\displaystyle 120 \sqrt{15}\)

Correct answer:

\(\displaystyle 120 \sqrt{15}\)

Explanation:

\(\displaystyle y^{2} = 12\) and \(\displaystyle y\) is positive, so 

\(\displaystyle y = \sqrt{12}\).

The greatest perfect square factor of 12 is 4, so the radical can be simplified:

\(\displaystyle y = \sqrt{4} \cdot \sqrt{3} = 2 \sqrt{3}\)

\(\displaystyle z^{2} = 5\), and \(\displaystyle z\) is positive, so \(\displaystyle z = \sqrt{5}\)

By the Power of a Power Property, 

\(\displaystyle (y z)^{3}\)

\(\displaystyle = y^{3} z^{3}\)

It is easiest to note that this can be broken up by the Product of Powers Principle, and evaluated by substitution:

\(\displaystyle y^{3} z^{3}\)

\(\displaystyle = y^{2+ 1} z^{2+ 1}\)

\(\displaystyle = y^{2 } \cdot y \cdot z^{2 } \cdot z\)

\(\displaystyle =12 \cdot \sqrt{12} \cdot 5 \cdot \sqrt{5}\)

\(\displaystyle =12 \cdot 5 \cdot \sqrt{12} \cdot \sqrt{5}\)

\(\displaystyle =60 \cdot \sqrt{60}\)

The greatest perfect square factor of 60 is 4, so the radical can be simplified:

\(\displaystyle 60 \cdot \sqrt{60}\)

\(\displaystyle =60 \cdot \sqrt{4} \cdot \sqrt{15}\)

\(\displaystyle =60 \cdot 2 \cdot \sqrt{15}\)

\(\displaystyle =120 \sqrt{15}\)

Example Question #121 : How To Find The Properties Of An Exponent

\(\displaystyle x^{2} = 75\)

\(\displaystyle y^{2} = 3\)

\(\displaystyle x\) and \(\displaystyle y\) are both positive.

Evaluate \(\displaystyle (4x +y) (4x -y)\).

Possible Answers:

\(\displaystyle 183\)

\(\displaystyle 297\)

\(\displaystyle 1,197\)

\(\displaystyle 1,083\)

Correct answer:

\(\displaystyle 1,197\)

Explanation:

By the difference of squares pattern:

\(\displaystyle (4x +y) (4x -y)\)

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

By the Power of a Power Principle,

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

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

\(\displaystyle =16 x^{2} - y^{2}\)

Substituting 75 and 3 for \(\displaystyle x^{2}\) and \(\displaystyle y^{2}\), respectively:

\(\displaystyle =16 (75)- 3\)

\(\displaystyle =1,200- 3\)

\(\displaystyle =1,197\)

Example Question #172 : Ssat Upper Level Quantitative (Math)

\(\displaystyle y ^{5} = -7\)

\(\displaystyle y^{20} = ?\)

Possible Answers:

\(\displaystyle -28\)

\(\displaystyle 2,401\)

\(\displaystyle 28\)

\(\displaystyle -2,401\)

Correct answer:

\(\displaystyle 2,401\)

Explanation:

By the Power of a Power Principle, 

\(\displaystyle (y ^{5} ) ^{4} = y ^{5 \cdot 4} = y ^{20}\)

Substituting \(\displaystyle -7\) for \(\displaystyle y ^{5}\), keeping in mind that an even power of any number must be positive:

\(\displaystyle y ^{20} = (y ^{5} ) ^{4} =( -7)^{4} = 7 ^{4} = 7 \cdot 7 \cdot 7 \cdot 7= 2,401\)

Example Question #124 : Properties Of Exponents

\(\displaystyle x> 0\) and \(\displaystyle y > 0\)

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

\(\displaystyle y^{2} = 18\)

Evaluate \(\displaystyle (x+ y) ^{2}\).

Possible Answers:

\(\displaystyle 50\)

\(\displaystyle 38\)

\(\displaystyle 144\)

\(\displaystyle 26\)

Correct answer:

\(\displaystyle 50\)

Explanation:

By the perfect square trinomial pattern,

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

\(\displaystyle =x^{2} +2xy+ y ^{2}\)

\(\displaystyle x^{2} = 8\) and \(\displaystyle y^{2} = 18\).

Also, by the Power of a Power Principle, 

\(\displaystyle (xy) ^{2} = x^{2} y^{2} = 8 \cdot 18 = 144\)

so, since \(\displaystyle x\) and \(\displaystyle y\) are both positive, 

\(\displaystyle xy = \sqrt{(xy) ^{2} }= \sqrt{144}= 12\).

Therefore, 

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

\(\displaystyle =x^{2} +2xy+ y ^{2}\)

\(\displaystyle = 8 +2 (12)+18\)

\(\displaystyle = 8 +24 +18\)

\(\displaystyle = 50\)

 

Example Question #181 : Algebra

\(\displaystyle y^{3} = -17\)

\(\displaystyle y^{9} = ?\)

Possible Answers:

\(\displaystyle 4,913\)

\(\displaystyle -4,913\)

\(\displaystyle 51\)

\(\displaystyle -51\)

Correct answer:

\(\displaystyle -4,913\)

Explanation:

By the Power of a Power Principle, 

\(\displaystyle (y ^{3} ) ^{3} = y ^{3 \cdot 3} = y ^{9}\)

Therefore, we substitute, keeping in mind that an odd power of a negative number is also negative:

\(\displaystyle y ^{9} = (y ^{3} ) ^{3}\)

\(\displaystyle = (-17) ^{3}\)

\(\displaystyle = - 17 ^{3}\)

\(\displaystyle = - (17 \cdot 17\cdot 17)\)

\(\displaystyle = -4,913\)

Example Question #183 : Algebra

\(\displaystyle x> 0\) and \(\displaystyle y > 0\)

\(\displaystyle x^{2} = 18\)

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

Evaluate \(\displaystyle (x- y) ^{2}\).

Possible Answers:

\(\displaystyle 50\)

\(\displaystyle 10\)

\(\displaystyle 2\)

\(\displaystyle 26\)

Correct answer:

\(\displaystyle 2\)

Explanation:

By the perfect square trinomial pattern,

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

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

\(\displaystyle x^{2} =1 8\) and \(\displaystyle y^{2} = 8\).

Also, by the Power of a Power Principle, 

\(\displaystyle (xy) ^{2} = x^{2} y^{2} = 18 \cdot 8 = 144\)

so, since \(\displaystyle x\) and \(\displaystyle y\) are both positive,

\(\displaystyle xy = \sqrt{(xy) ^{2} }= \sqrt{144}= 12\).

Therefore, 

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

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

And, substituting:

\(\displaystyle x^{2} -2xy+ y ^{2}\)

\(\displaystyle =18 -2 (12)+8\)

\(\displaystyle =18 -24 +8\)

\(\displaystyle = 2\)

Example Question #184 : Algebra

\(\displaystyle t^{6} = 144\)

\(\displaystyle x^{6}= 81\)

\(\displaystyle t > 0, x< 0\)

Evaluate the expression \(\displaystyle (t-x) (t^{2}+tx+x^{2})\).

Possible Answers:

\(\displaystyle 3\)

\(\displaystyle 21\)

\(\displaystyle -3\)

\(\displaystyle -21\)

Correct answer:

\(\displaystyle 21\)

Explanation:

Multiply out the expression by using multiple distributions and collecting like terms:

\(\displaystyle (t-x) (t^{2}+tx+x^{2})\)

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

\(\displaystyle = t \cdot t^{2}+ t \cdot tx+ t \cdot x^{2} - x \cdot t^{2}- x \cdot tx- x \cdot x^{2}\)

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

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

\(\displaystyle = t^{3} - x^{3}\)

Since \(\displaystyle (t^{3} ) ^{2} = t ^{3 \cdot 2 } = t^{6}\) by the Power of a Power Principle,

\(\displaystyle t^{3} = \pm \sqrt{ t^{6}} = \pm \sqrt{144} = \pm 12\).

However, \(\displaystyle t\) is positive, so \(\displaystyle t^{3}\) is as well, so we choose \(\displaystyle t^{3} = 12\).

Similarly, 

\(\displaystyle x^{3} = \pm \sqrt{x^{6}} = \pm \sqrt{81} = \pm 9\).

However, since \(\displaystyle x\) is negative, as an odd power of a negative number, \(\displaystyle x^{3}\) is as well, so we choose \(\displaystyle x^{3} = -9\).

Therefore, substituting:

\(\displaystyle (t-x) (t^{2}+tx+x^{2}) = t^{3} - x^{3} = 12 - (-9) = 21\) 

Example Question #121 : Properties Of Exponents

\(\displaystyle A\) and \(\displaystyle B\) are both positive integers; A is odd. What can you say about the number 

\(\displaystyle (A + B + 1)^{A+B+1}\) ?

Possible Answers:

\(\displaystyle (A + B + 1)^{A+B+1}\) is odd if \(\displaystyle B\) is odd, and even if \(\displaystyle B\) is even.

\(\displaystyle (A + B + 1)^{A+B+1}\) is even if \(\displaystyle B\) is odd, and odd if \(\displaystyle B\) is even.

\(\displaystyle (A + B + 1)^{A+B+1}\) is even if \(\displaystyle B\) is even, and can be odd or even if \(\displaystyle B\) is odd.

\(\displaystyle (A + B + 1)^{A+B+1}\) is odd if \(\displaystyle B\) is odd, and can be odd or even if \(\displaystyle B\) is even.

\(\displaystyle (A + B + 1)^{A+B+1}\) is even if \(\displaystyle B\) is odd, and can be odd or even if \(\displaystyle B\) is even.

Correct answer:

\(\displaystyle (A + B + 1)^{A+B+1}\) is odd if \(\displaystyle B\) is odd, and even if \(\displaystyle B\) is even.

Explanation:

If \(\displaystyle B\) is odd, then \(\displaystyle A + B +1\), the sum of three odd integers, is odd; an odd number taken to any positive integer power is odd.

If \(\displaystyle B\) is even, then \(\displaystyle A + B +1\), the sum of two odd integers and an even integer, is even; an even number taken to any positive integer power is even. 

Therefore, \(\displaystyle (A + B + 1)^{A+B+1}\) always assumes the same odd/even parity as \(\displaystyle B\).

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