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Given the function f(x) = 4(x + 3) - 5, solve for the inverse function when x = 3.
Solution:
An inverse function reverses the operation done by a particular function. In other words, the inverse function undoes the action of the other function.
Given: Function is f(x) = 4(x + 3) - 5
First replace f(x) with y.
⇒ y = 4(x + 3) - 5
Using the multiplicative distributive property
⇒ y = 4x + 12 - 5
⇒ y = 4x + 7
Next replace x with y and y with x.
⇒ x = 4y + 7
Solving for y, we get,
⇒ 4y = x - 7
⇒ y = (x - 7)/4
Finally replace y with f -1(x).
⇒ f -1(x) = (x - 7)/4
Given x = 3,
y = (3 - 7)/4
y = -4/4
y = -1
Verification:
(f ∘ f -1)(x)= x
(f ∘ f -1)(x)= f [f -1(x)]
= f [(x - 7)/4]
= f [x/4 - 7/4]
= 4[x/4 - 7/4] +7
= x - 7 + 7
= x
Therefore, the inverse function when x = 3 is -1.
Given the function f(x) = 4(x + 3) - 5, solve for the inverse function when x = 3.
Summary:
If the function f(x) = 4(x + 3) - 5, then the inverse function when x = 3 is -1.
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