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Express your answer as a polynomial in standard form.

f(x) = -5x + 14
g(x) = x2 + 6x – 7
Find: f(g(x))

1 Answer

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Answer:

f(g(x)) = -5x^2 - 30x + 49

Explanation:

f(g(x)) is a composite function, where 'x' in f(x) is replaced by 'x^2 + 6x - 7' because the latter expression is now the input to f(x).

Write out f(x) = -5x + 14, and then replace each 'x' with '( )'

f( ) = -5( ) + 14

Now insert 'g(x)' into the first set of parentheses and 'x^2 + 6x - 7' into the second set of parentheses:

f( ) = -5( ) + 14 becomes:

f(g(x) = -5(x^2 + 6x - 7) + 14. After simpification, this becomes

f(g(x)) = -5x^2 - 30x + 35 + 14, or

f(g(x)) = -5x^2 - 30x + 49

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