F(x)+G(x)=(-5x\(^5\)+7x^3+x^2-2x+12)+(-4x^4+x^3+7x^2+8x-9)
=(-5x^5)+(7x^3+x^3)+(x^2+7x^2)+(-2x+8x)+(
-4x^4)+(12+-9) =(-5x^5)+8x^3+8x^2+6x+(-4x^4)+3. CHÚC BẠN HỌC TỐTF(x)+G(x)=(-5x3+7x3+x2-2x+12)+(-4x4+x3+7x2+8x-9)=-5x5-4x4+8x3+8x2+6x+3
\(F\left(x\right)+G\left(x\right)=\left(-5x^5+7x^3+x^2-2x+12\right)+\left(-4x^4+x^3+7x^2+8x-9\right)\)
= \(-5x^5+7x^3+x^2-2x+12-4x^4+x^3+7x^2+8x-9\)
= \(=-5x^5+\left(7x^3+x^3\right)+\left(x^2+7x^2\right)+\left(-2x+8x\right)+\left(12-9\right)-4x^4\)
= \(-5x^5-4x^4+8x^3+8x^2+6x+3\)
Cho mk hỏi chút trc x3 là + hay - vậy
F(x) + G(x)= (-5x^5 + 7x^3 + x^2 - 2x + 12) + (-4x^4 + x^3 + 7x^2 + 8x -9)
= -5x^5 + 7x^3 + x^2 - 2x + 12 - 4x^4 + x^3 + 7x^2 + 8x -9
=(7x^3 + x^3) + (x^2 + 7x^2) + (-2x + 8x) + (12 - 9) - 5x^5 - 4x^4
= 8x^3 + 8x^2 + 6x + 3 - 5x^5 - 4x^4.
Chúc bạn học tốt!