Question

F(x)=8_-4x-x^3. g(x)=x^2+7x-9. Find f(x)+g(x)
A. x^3+x^2+3x-1
B. -x^3+x+3x-1
C. -x^3+x^2+11x-9
D. 8x^2+3x-9x^3

Answer 1

$(8 - 4x - {x}^{3} ) + ( {x}^{2} + 7x - 9) \\ = - {x}^{3} + {x}^{2} - 4x + 7x + 8 - 9 \\ = - {x}^{3} + {x}^{2} + 3x - 1$
$(8x - 4x - {x}^{3} ) + ( {x}^{2} + 7x - 9) \\ - {x}^{3} + {x}^{2} + 8x - 4x + 7x - 9 \\ - {x}^{3} + {x}^{2} + 11x - 9$
The answer is either B, and you forgot to put in the ^2 in the answer choice, or C, and you forgot to put an x where there is a _ in the question.

Check the actual question (the one you recieved, not the one posted here) and see where the mistakes are. If f(x) = 8x - 4x - x^3, then your answer is C. However, if B is actually -x^3 + x^2 + 3x - 1, then the answer is B.