Q. Let f(x)=2x+3 and let g(x)=x2−4x. Which of the following is equivalent to g(f(x)) ?Choose 1 answer:(A) 4x2+4x−3(B) 4x2−8x−3(C) 4x2+4x+21(D) 2x2−8x+3
Substitute f(x) into g(x): First, substitute f(x) into g(x) to get g(f(x)).g(f(x))=g(2x+3)
Plug in 2x+3: Now, plug in 2x+3 wherever there's an x in g(x).g(2x+3)=(2x+3)2−4(2x+3)
Expand and distribute: Expand the square and distribute the −4.g(2x+3)=(2x+3)(2x+3)−8x−12
Multiply out the terms: Multiply out the terms.g(2x+3)=4x2+6x+6x+9−8x−12
Combine like terms: Combine like terms.g(2x+3)=4x2+12x−8x+9−12
Finish combining: Finish combining like terms.g(2x+3)=4x2+4x−3
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