Question

What is the value of x in log2 (x)-3=1

A) 2^2
b) 2^4
c) 2^3
d) 2^1

Answer 1

b) 2^4

Explanation:

`(\log_2 x) - 3 = 1`

`\log_2 x = 4`

`\log_2 x = 4`

`2^4 = x`

`x = 2^4`

Answer 2

`Domain:x > 0\\\\\log_2x-3=1\qquad\text{add 3 to both sides}\\\\\log_2x=4\qquad\text{use de}\text{finition of logarithm}:\ \log_ab=c\iff a^c=b\\\\\boxed{x=2^4}\to\boxed{b)}`