Đáp án:
Giải thích các bước giải:
a) `A(x)=-2x^4 - 3x^2 +7x-2`
`B(x)=2x^4 + 3x^2 + 4x-5`
b) $M(x)=-3x^2\:-\:2x^4\:-2\:+\:7x+\:3\:x^2\:+\:4x\:-5\:+\:2x^4$
`=-2x^4+2x^4-3x^2+3x^2+7x+4x-2-5`
`=-2x^4+2x^4+7x+4x-2-5`
`=7x+4x-2-5`
`=11x-7`
* `11x-7=4 <=>11x=11=>x=1`
c) `C(x)=3x^2+2x^4+2-7x+3x^2+4x-5+2x^4`
`=2x^4+2x^4+6x^2-7x+4x+2-5`
`=4x^4+6x^2-7x+4x+2-5`
`=4x^4+6x^2-3x-3`