Question

Find the value of x in the given expression.
$2^x$ = 128

• A. 3
• B. 4
• C. 5
• D. 7

Answer 1

The correct option is D 7

Let us substitute x = 3 in the given expression.
$2^3$ = 2 $\times$ 2 $\times$ 2 = 8
This does not satisfy the RHS, 128, of the given expression.


Let us substitute x = 4 in the given expression.
$2^4$ = 2 $\times$ 2 $\times$ 2 $\times$ 2 = 16
This does not satisfy the RHS, 128, of the given expression.

Let us substitute x = 5 in the given expression.
$2^5$ = 2 $\times$ 2 $\times$ 2 $\times$ 2 $\times$ 2 = 32
This does not satisfy the RHS, 128, of the given expression.

Let us substitute x = 7 in the given expression.
$2^7$ = 2 $\times$ 2 $\times$ 2 $\times$ 2 $\times$ 2 $\times$ 2 $\times$ 2
= 128
This satisfies the RHS, 128, of the given expression.

Hence, the value of x is 7 in the given expression.