Let f(x) = x − 2 and g(x) = x2 − 7x − 9. Find f(g(−1)).
We will use the concept of functions to solve the given question.
Answer: If f(x) = x − 2 and g(x) = x2 − 7x − 9, then f(g(-1)) = -3.
Let us solve it step by step.
Explanation:
Given:
f(x) = x − 2 ------------ (1)
g(x) = x2 − 7x − 9 ------------- (2)
Both f(x) and g(x) are functions of x and dependent on x.
We have to find composite function f(g(x)).
f(g(x)) = {g(x)} - 2
⇒ f(g(x)) = (x2 − 7x − 9) - 2 [From (1) and (2)]
⇒ f(g(x)) = x2 − 7x − 9 - 2
⇒ f(g(x)) = x2 − 7x − 11
Now let us solve this for x = -1.
f(g(-1)) = (-1)2 − 7(-1) − 11
⇒ f(g(-1)) = 1 + 7 - 11
⇒ f(g(-1)) = -3
Thus, if f(x) = x − 2 and g(x) = x2 − 7x − 9, then f(g(-1)) = -3.
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