Use this equation: A=3.14159r^2
For this case we must find the inverse of the following function:

We follow the steps below:
Replace f(x) with y:

We exchange the variables:

We solve for "y":

Multiply by -2 on both sides of the equation:

We raise both sides of the equation to the square to eliminate the radical:

We subtract 3 from both sides of the equation:

We change y by f ^ {- 1} (x):

Answer:
Answer:
The number is 12
Step-by-step explanation:
Let x = number
2x+16 = 40
Subtract 16 from each side
2x+16-16 =40-16
2x = 24
Divide by 2
2x/2 =24/2
x = 12
Makes his grass greener and healthier