Đáp án:
↓↓
Giải thích các bước giải:
` (x-1)(x-3)(x-4)(x-5)+(x-3)(x-6)(x+8)+(x+18)(x+19)+(x-3)³-(x-9)³`
`=(x²-4x+3)(x²-9x+20)+(x²-9x+18)(x+8)+x²+37x+342+(x-3-x+9)[(x-3)²+(x-3)(x-9)+(x-9)²]`
`=x⁴-9x³+20x²-4x³+36x²-80x+3x²-27x+60+x³+8x²-9x²-72x+18x+144+x²+37x+342+6.(3x²-36x+117)` `=x⁴-9x³+20x²-4x³+36x²-80x+3x²-27x+60+x³+8x²-9x²-72x+18x+144+x²+37x+342+18x²-216x+702`
`=x⁴+(-9x³-4x³+x³)+(20x²+36x²+3x²+8x²-9x²+x²+18x²)+(-80x-27x-72x+18x+37x-216x)+(60+144+342+702)`
`=x⁴-12x³+77x²-340x+1248`
