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

Question

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

Video Solution

Solution Steps

00:07 Let's simplify this expression step by step.
00:11 If you have one divided by a number with a negative exponent...
00:15 ...it becomes the same base with a positive exponent.
00:19 So, let's apply this to our problem.
00:23 Four to the power of negative exponent becomes four with a positive exponent.
00:29 Next, we'll break down four to two squared.
00:33 Remember, when there's a power of a power, multiply the exponents.
00:39 Let's see how this works in our exercise.
00:44 Now, solve the multiplication of the exponents.
00:49 When multiplying powers with the same base...
00:53 ...add the exponents together for the result's power.
00:58 Let's apply this to finish our problem.
01:02 Solve the exponent, and that's how you find the solution!

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