1
a)(5y-1)(3y+9)=15y²+45y-3y-9=15y²+42y-9
b)(x²-16)(x+7)=x³+7x²-16x-112
2
a)0,6m-m²+3mn
m=-4,n=0,8
0,6*(-4)-(-4)²+3*(-4)*0,8=-2,4-16-9,6=-28
b)(4a²-4ab+b²)/(4a²-b²)=(2a-b)²/[(2a-b)(2a+b)]=(2a-b)/(2a+b)
a=1/11,b=-9/11
(2/11+9/11):(2/11-9/11)=1:(-7/11)=-11/7
3
a)(57x^4y^7/(-8x^6y^5)=-57y²/(8x²)
б)(4c+3d)/(-3d-4c)²=(4c+3d)/(3d+4c)²=1/(3s+4c)
в)(5a+2b)²/(-2b-5a)²=(5a+2b)²/(2b+5a)²=1
г)(3a-6b)/(2ab-a²-ac+2bc)=(3a-6b)/[a(2b-a)+c(2b-a)]=3(a-2b)/[(2b-a)(a+c)]=
=-3/(a+c)