Question the-fu

2.1 Nonlinear Functions - Function composition and evaluation
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The functions f and g are defined by the given equations.

fx=3+|-2x-x2|

gw=|-ww-1|-w+5

If f(-4)=c, where c is a constant, what is the value of gc?

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The functions f and g are defined by the given equations. f x = 3 +

Hard-difficulty · SAT Math · Nonlinear Functions — Function composition and evaluation. Read the question above, select your answer, and check the full explanation below to understand exactly why the correct choice works.

Answer explanation

The correct answer is - 4.9 . The value of f-4 is the value of fx when x=-4. Substituting - 4 for x in the equation fx=3+-2x-x2 yields f-4=3+-2-4--42, or f-4=3+-8, which is equivalent to f-4=3+8, or f-4=11. Since it's given that f-4=c, it follows that c = 11 and the value of gc is the value of g11. Substituting 11 for w in the equation gw=-ww-1-w+5 yields g11=-1111-1-11+5, or g11=-1.1-6, which is equivalent to g11=1.1-6, or g11=-4.9. Note that -4.9 and -49/10 are examples of ways to enter a correct answer.