Question

If ƒ(x ) = 3x + 1 and ƒ -1 = , then ƒ -1(7) =

Answer 1

f(x) = 3x + 1

let f(x) = y

y = 3x + 1

y - 1 = 3x

3x = y - 1

x = (y - 1)/3

From y = f(x), x = f⁻¹(y)

x = (y - 1)/3

f⁻¹(y) = (y - 1)/3

f⁻¹(7) = (7 - 1)/3 = 6/3 = 2

f⁻¹(7) = 2