ПОМОГИТЕ ПОЖАЛУЙСТА С РЕШЕНИЕМ !

Ответ:

1)-3х²(-3х²-5х+2)=9х^4+15х³-6х²

2)(-8а³+0,3b)(-2,5b²)=20a³b²-0,75b³

3)(2,4x²y-5y²-0,6x)•12x²y²=28,8x^4y³-60x²y^4-7,2x³y²

4)-2/3m²n(3,9m²-0,9n+57)=-2,6m^4n+0,6m²n²-38m²n

2) -5x(x²-3xy+4y²)+x²(x-5y)=-5x³+15x²y-20xy²+x³-5x²y=-4x³+10x²y-20xy²;

-4x³+10x²y-20xy²=-4•(-2)³+10(-2)²•4-20(-2)•4²=32+160+640=832

3)6m(2m²-m+4)-(8m³+2m²-7)-2m(2m²-4m+12)=12m³-6m²+24m-8m³-2m²+7-4m³+8m²-24m=7

4)1)(x+2)/8-(x-2)/2=10-(x+3)/4

(x+2)-4(x-2)=80-2(x+3)

x+2-4x+8=80-2x-6

x-4x+2x=80-6-2-8

-x=54; x=-54

2)12x+10x(5-4x)=5x(-8x+1)-114

12x+50x-40x²=-40x²+5x-114

57x=-114; x=-2