### Toán Lớp 8: (x-1)(x-3)(x-4)(x-5)+(x-3)(x-6)(x+8)+(x+18)(x+19)+(x-3)^3-(x-9)^3 Rút gọn nào =))

Toán Lớp 8: (x-1)(x-3)(x-4)(x-5)+(x-3)(x-6)(x+8)+(x+18)(x+19)+(x-3)^3-(x-9)^3
Rút gọn nào =))

TRẢ LỜI

1. truongthanhhung
$\text{Giải đáp:}$
(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

Trả lời
2. cobebongdem
Giải đáp:
↓↓
Lời giải và giải thích chi tiết:
(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

Trả lời