Given the function f(x) = −2x + 4, find x if f(x) = 20
-2x+4=20
-2x=20-4
-2x=16 divide with -2
x=16/(-2)
x= -8
find f^-1 f(x)=5
To find the value of x when f(x) = 20, you can set up the equation:
-2x + 4 = 20
To solve for x, you need to isolate x on one side of the equation.
First, subtract 4 from both sides of the equation:
-2x + 4 - 4 = 20 - 4
-2x = 16
Next, divide both sides of the equation by -2 to solve for x:
-2x / -2 = 16 / -2
x = -8
So, x = -8 is the value that satisfies the equation f(x) = 20 when f(x) = -2x + 4.