tolong dibantu yaa...
a. f(x) = y
[tex] \frac{2x + 5}{x - 1} = y[/tex]
2x + 5 = y( x - 1 )
2x + 5 = yx - y
2x - yx = -y - 5
( 2 - y ) x = -y - 5
[tex]x = \frac{ - y - 5}{2 - y} \\ f {}^{ - 1} (x) = \frac{ - x - 5}{2 - x} [/tex]
b. f(x) = y
x² - 6x + 8 = y
x² - 6x + 9 - 1 = y
( x - 3 )² - 1 = y
( x - 3 )² = y + 1
[tex]x - 3 = \sqrt{y + 1} \\ x = 3 + - \sqrt{y + 1} \\ f {}^{ - 1} (x) = 3 + - \sqrt{x + 1} [/tex]
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