Đáp án:

Giải thích các bước giải:

 `a) A(x) = 5x^4 - 7x^2 - 3x - 6x^2 + 11x - 30`

`=5x^4 - (7x^2 + 6x^2) + (11x - 3x)-30`

`=5x^4 - 13x^2 + 8x -30`

`B(x) = -11x^3 + 5x - 10 + 13x^4 - 2 + 20x^3 - 34x`

`B(x) = 13x^4 + (20x^3 - 11x^3) -(34x - 5x) - 10-2`

`B(x) = 13x^4 + 9x^3 - 29x -12`

`b)A(x) - B(x)`

`=(5x^4 - 13x^2 + 8x -30) - ( 13x^4 + 9x^3 - 29x -12)`

`=5x^4 - 13x^2 + 8x -30 - 13x^4 - 9x^3 + 29x +12`

`=(5x^4 - 13x^4)- 9x^3 - 13x^2 + (8x + 29x) - 30+12`

`=-8x^4 - 9x^3 - 13x^2 + 37x - 18`