mohon bantuannya yaa terima kasih:)

f(x) = 1/√(2x + 1)
1/√(2x + 1) = y
y√(2x + 1) = 1 =====> kedua ruas dikuadratkan
y^2 (2x + 1) = 1
2xy^2 + y^2 = 1
2xy^2 = 1 - y^2
x = (1 - y^2)/(2y^2)
f^-1(x) = (1 - x^2)/(2x^2)
g(x) = f^-1(x)
g(5) = (1 - 5^2)/(2.5^2) = (1 - 25)/(2.50) = -24/50 = -12/25