Evaluate the Fraction: Finding 1/(-2)^7 Step by Step

Question

1(2)7=? \frac{1}{(-2)^7}=?

Video Solution

Solution Steps

00:00 Simply
00:03 1 divided by number (A) to the power of (N)
00:07 equals the same base (A) with the same exponent (N) but negative
00:11 We will use this formula in our exercise
00:19 We'll break down -2 into factors -1 and 2
00:29 When there's a power on a product of numbers, they all rise to that power
00:33 We will use this formula in our exercise
00:43 We'll be left with minus
00:46 And this is the solution to the question

Step-by-Step Solution

To begin with we deal with the expression in the denominator of the fraction. Making note of the power rule for exponents (raising an exponent to another exponent):

(am)n=amn (a^m)^n=a^{m\cdot n} We obtain the following:

(2)7=(12)7=(1)727=127=27 (-2)^7=(-1\cdot2)^7=(-1)^7\cdot2^7=-1\cdot2^7=-2^7

We then return to the initial problem and apply the above information:

1(2)7=127=11127=127 \frac{1}{(-2)^7}=\frac{1}{-2^7}=\frac{1}{-1}\cdot\frac{1}{2^7}=-\frac{1}{2^7}

In the last step we remember that:

11=1 \frac{1}{-1}=-1

Next, we remember the Negative Exponent rule ( raising exponents to a negative power)

an=1an a^{-n}=\frac{1}{a^n} We apply it to the expression we obtained in the last step:

127=27 -\frac{1}{2^7}=-2^{-7} Let's summarize the steps of the solution:

1(2)7=127=27 \frac{1}{(-2)^7}=-\frac{1}{2^7} = -2^{-7}

Therefore, the correct answer is option C.

Answer

(2)7 (-2)^{-7}