Which function below is the inverse of f(x) = x2 − 25?
f(x) = x² - 25
y = x² - 25
x = y² - 25
+ 25 + 25
x + 25 = y²
√x + 25 = √y²
±√x + 25 = y
±√x + 25 = f⁻¹(x)
\(f(x) = x^{2} - 25\)
Let f(x) = y
thus y = \(x^{2} - 25\)
switch the position of y and x in the equation
\(x = y ^{2} - 25\)
then solve for y in this case
\(x + 25 = y^{2}\)
∴ y=\(\sqrt{x + 25}\)
Thus, \(f^{-1} (x) = \sqrt{x + 25}\)