Inverse Function Example 4


Question:
(b) if  f : x x + 9 x 5 ,   x 5 ,  find  f 1 ( 3 ) .

Solution:
(a)
f (x) = x– 2
Let y = f -1 (5)
f (y) = 5
y – 2 = 5
y = 7
therefore, f -1 (5) = 7

(b)
f ( x ) = x + 9 x 5 Let  y = f 1 ( 3 ) f ( y ) = 3 y + 9 y 5 = 3 y + 9 = 3 y 15 2 y = 24 y = 12 f 1 ( 3 ) = 7


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