Question

Consider function f.

f(x) = square root of 7x – 21
Place the steps for finding f-1(x) in the correct order.

Answer 1

• f⁻¹(x) = 1/7x² + 3

Explanation:

Given

• f(x) =
  `√(7x-21)`

To find

• Inverse of f(x)

Solution

Change f(x) → x, and x → y, and solve for y:

• x =
  `√(7y -21)`
• x² = 7y - 21
• 7y = x² + 21
• y = 1/7x² + 3

y = f⁻¹(x)

• f⁻¹(x) = 1/7x² + 3