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

Question

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

Video Solution

Solution Steps

00:08 Let's simplify this problem together.
00:11 One divided by a number, A, raised to the power of N.
00:16 This equals the base, A, to the power of negative N.
00:21 Let's use this formula in our exercise step by step.
00:27 First, split negative two into factors: negative one and two.
00:37 Remember, if a product is raised to a power, each factor is also raised to that power.
00:43 Now, apply this rule to our exercise.
00:51 You'll find that we're left with a minus.
00:55 And that's how we solve this problem!

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}