For the function f(x)=-4sqrtx-1, find the inverse function.

Given function: .

We need to find the inverse of the given function f(x).

Let us write the function in terms of x and y first.

Now, in order to find the inverse, we need to switch x and y, we get

Now, we need to solve it for y.

In order to solve it for y, we need to isolate it for y.

Adding 1 on both sides, we get

Dividing both sides by -4, we get

In order to get rid square root from right side, we need to square both side.

Or

Therefore, inverse function is

.

47 - 90 = 43

43 - 180 = x

x = 137