SOLUTION: hi can you help me with this question, thank you :) 1.)f(x)+2(x-8)^2+5 what is f^-1(7)?

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Question 1090249: hi can you help me with this question, thank you :)
1.)f(x)+2(x-8)^2+5 what is f^-1(7)?
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

1.)
f%28x%29=2%28x-8%29%5E2%2B5 what is f%5E-1%287%29
first find f%5E-1%28x%29
f%28x%29=y=2%28x-8%29%5E2%2B5
y=2%28x-8%29%5E2%2B5...........swap x and y
x=2%28y-8%29%5E2%2B5
x-5=2%28y-8%29%5E2
%28x-5%29%2F2=%28y-8%29%5E2
sqrt%28%28x-5%29%2F2%29=y-8
y=± sqrt%28%28x-5%29%2F2%29%2B8

f%5E-1%28x%29=± sqrt%28%28x-5%29%2F2%29%2B8
now find f%5E-1%287%29
f%5E-1%287%29=± sqrt%28%287-5%29%2F2%29%2B8
f%5E-1%287%29=± 9