Question

Let f(x) = 8(1.5)^x/2. For what value of x dose f(x) = 40.5? x= ___

Answer 1

When x = 8, f(x) = 40.5

Explanation:

f(x) = 8(1.5)^x/2

To find value of x when f(x) = 40.5:

=> 8(1.5)^x/2 = 40.5

=> (1.5)^x/2 = 40.5/8

=> (1.5)^x/2 = 81/16

=> ln(1.5^(x/2)) = ln(81/16)

=> (x/2) ln(1.5) = ln(81/16)

=> x/2 = ln(81/16)/ln(1.5)

=> x/2 = 4

=> x = 8