If f(x) and f-1(x) are inverse functions of each other and f(x)=2x+5, what is f-1(8)?

The correct option is and the value of  .

Given: If and are inverse functions of each other and .

According to question:

Now,

Hence, the value of .

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The required inverse of the function at when x = 8 is 3/2: Option B is correct

Given the function g(x)=2x+5, first we need to find the inverse of the function:

Let y = g(x)

y= 2x + 5

Replace y with x

x = 2y + 5

Make y the subject of the formula

2y = x - 5

y = (x - 5)/2

Hence the inverse of the expression is f^{-1}x = (x - 5)/2

Substitute x = 8 into the result

f^{-1}(8) = (8 - 5)/2

f^{-1}(8)  = 3/2

Hence the required inverse of the function at when x = 8 is 3/2

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