Solving for Reciprocal: Calculating (7/8) to the Negative Power

Question

(78)2=? (\frac{7}{8})^{-2}=\text{?}

Video Solution

Solution Steps

00:00 Simplify the following problem
00:03 In order to eliminate a negative exponent
00:08 We'll flip the numerator and the denominator so that the exponent will become positive
00:12 We'll apply this formula to our exercise
00:17 When raising a fraction to a power, both the numerator and the denominator are raised to that power
00:24 We'll apply this formula to our exercise
00:32 We'll break down each exponent and then proceed to solve
00:40 This is the solution

Step-by-Step Solution

To solve the problem of evaluating (78)2(\frac{7}{8})^{-2}, we'll proceed with these steps:

  • Step 1: Convert the negative exponent into a positive exponent by taking the reciprocal of the base.
  • Step 2: Evaluate the expression obtained after the conversion.

Now, let's work through each step:

Step 1: Convert the negative exponent to a positive exponent using the reciprocal:
Using the property (ab)n=(ba)n(\frac{a}{b})^{-n} = (\frac{b}{a})^{n}, we have:

(78)2=(87)2 (\frac{7}{8})^{-2} = (\frac{8}{7})^{2}

Step 2: Calculate the positive power:

(87)2=8272=6449(\frac{8}{7})^{2} = \frac{8^2}{7^2} = \frac{64}{49}

Thus, the solution to the problem is:
(78)2=6449 (\frac{7}{8})^{-2} = \frac{64}{49}

Extra step to express 6449\frac{64}{49} as a mixed number:

64÷49=1 64 \div 49 = 1 remainder 1515, so 6449=11549\frac{64}{49} = 1 \frac{15}{49} .

Therefore, the simplified solution to the expression (78)2(\frac{7}{8})^{-2} is 11549 1 \frac{15}{49} .

Answer

11549 1\frac{15}{49}