SOLUTION: f(x)= 3(x^2+5) Find f^-1(x), f^-1(27)

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Question 604580: f(x)= 3(x^2+5) Find f^-1(x), f^-1(27)
Answer by nerdybill(7384) About Me  (Show Source):
You can put this solution on YOUR website!
f(x)= 3(x^2+5) Find f^-1(x), f^-1(27)
.
Find f^-1(x):
y = 3(x^2+5)
switch the variables and solve for y:
x = 3(y^2+5)
x/3 = y^2+5
x/3 - 5 = y^2
sqrt(x/3 - 5) = y
or
f%5E-1%28x%29+=+sqrt%28x%2F3+-+5%29
.
finding f^-1(27):
f%5E-1%28x%29+=+sqrt%28x%2F3+-+5%29
f%5E-1%2827%29+=+sqrt%2827%2F3+-+5%29
f%5E-1%2827%29+=+sqrt%289+-+5%29
f%5E-1%2827%29+=+sqrt%284%29
f%5E-1%2827%29+=+2 (that's plus or minus 2)