Verified answer

5(3-5a)²-5(3a-7)(3a+7)=5(9-30а+25а²)-5(9а²-49)=45-150а+125а²-45а²+245=

(125а²-45а²)-150а+(45+245)=80а²-150а+290

(а+1)²+3(а-1)²-5(а+1)(а-1)=а²+2а+1+3(а²-2а+1)-5(а²-1)=а²+2а+1+3а²-6а+3-5а²+5=

(а²+3а²-5а²)+(2а-6а)+(1+3+5)=-а²-4а+9

(m-1)²-4(m+1)²-6(m+1)(m-1)=m²-2m+1-4(m²+2m+1)-6(m²-1)=m²-2m+1-4m²-8m-4-6m²+6=(m²-4m²-6m²)+(-2m-8m)+(1-4+6)=-9m²-10m+3

5(1-y)²-(3+y)²-3(1-y)(1+y)=5(1-2y+y²)-(9+6y+y²)-3(1-y²)=5-10y+5y²-9-6y-y²-3+3y²=

(5y²-y²+3y²)+(-10y-6y)+(5-9-3)=7y²-16y-7

5(1+m)(1-m)-(2-m)²-8(1-m)²=5(1-m²)-(4-4m+m²)-8(1-2m+m²)=5-5m²-4+4m-m²-8+16m-8m²=(-5m²-m²-8m²)+(4m+16m)+(5-4-8)=-14m²+20m-7

5(9-30а+25а²)-5(9а²+21а-21а-49)

45-150а+125а²-45а²+245

80а²-150а+290

(а+1)²+3(а-1)²-5(а+1)(а-1)

а²+2а+1+3(а²-2а+1)-5(а²-1)

а²+2а+1+3а²-6а+3-5а²+5

-а²-4а+9

(m-1)²-4(m+1)²-6(m+1)(m-1)

m²-2m+1-4(m²+2m+1)-6(m²-1)

m²-2m+1-4m²-8m-4-6m²+6

-9m²-10m+3

5(1-y)²-(3+y)²-3(1-y)(1+y)

5(1-2y+y²)-9-6y-y²-3(1-y²)

5-10y+5y²-9-6y-y²-3+3y²

7y²-16y-7

5(1+m)(1-m)-(2-m)²-8(1-m)²

5(1-m²)-4+4m-m²-8(1-2m+m²)

5-5m²-4+4m-m²-8+16m-8m²

-14m²+20m-7