Solve Fraction with Negative Exponent: 2/4^(-2)

Question

242=? \frac{2}{4^{-2}}=\text{?}

Video Solution

Solution Steps

00:00 Simplify the expression
00:03 1 divided by a number with a negative exponent
00:06 equals the same base with the same exponent but positive
00:09 We'll use this formula in our exercise
00:15 4 with a negative exponent becomes 4 with a positive exponent
00:22 Let's break down 4 to 2 squared
00:25 When there's a power of a power, the exponents are multiplied
00:32 We'll use this formula in our exercise
00:37 Let's solve the multiplication of exponents
00:42 When multiplying powers with equal bases
00:46 The power of the result equals the sum of the exponents
00:51 We'll use this formula in our exercise
00:55 Let's solve the exponent, and that's the solution to the question

Step-by-Step Solution

First, let's note that 4 is a power of 2:

4=22 4=2^2 therefore we can perform a conversion to a common base for all terms in the problem,

Let's apply this:

242=2(22)2 \frac{2}{4^{-2}}=\frac{2}{(2^2)^{-2}} Next, we'll use the power law for power of power:

(am)n=amn (a^m)^n=a^{m\cdot n} and we'll apply this law to the denominator term we got in the last step:

2(22)2=222(2)=224 \frac{2}{(2^2)^{-2}}=\frac{2}{2^{2\cdot(-2)}}=\frac{2}{2^{-4}} where in the first step we applied the above law to the denominator and in the second step we simplified the expression we got,

Next, we'll use the power law for division between terms with identical bases:

aman=amn \frac{a^m}{a^n}=a^{m-n} and we'll apply this law to the last expression we got:

224=21(4)=21+4=25 \frac{2}{2^{-4}}=2^{1-(-4)}=2^{1+4}=2^5

Therefore the correct answer is answer B.

Answer

242 2\cdot4^2