SOLUTION: Use the function f(x) = 4x-8 What is the value of f –1(–2)?

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Question 735573: Use the function
f(x) = 4x-8
What is the value of f –1(–2)?

Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
f%28x%29+=+4x-8
What is the value of f%5E%28-1%29%28-2%29?
first find inverse f%5E%28-1%29%28x%29

f%28x%29+=+4x-8 or y+=+4x-8
y+=+4x-8..switch x and y
x+=+4y-8....solve for y
x%2B8+=+4y
x%2F4%2B8%2F4+=+y
x%2F4%2B2+=+y
so inverse of f%28x%29=4x-8 is f%5E%28-1%29%28x%29%7D=x%2F4%2B2+
now find f%5E%28-1%29%28-2%29
f%5E%28-1%29%28-2%29=x%2F4%2B2+...plug in -2 for x
f%5E%28-1%29%28-2%29=-2%2F4%2B2+
f%5E%281%29%282%29=-1%2F2%2B2+
f%5E%281%29%282%29=-1%2F2%2B4%2F2+
f%5E%281%29%282%29=3%2F2+