25(x+y)^2+16(x-y)^2=

1
25(x+y)^2+16(x-y)^2
=25(x^+2xy+y^)+16(x^-2xy+y^)
=25x^+50xy+25y^+16x^-32xy+16y^
=41x^+18xy+41y^
2
4y(y-x)^2-6y(x-y)^3
=4y(y^-2xy+x^)-6y(x^3-3x^y+3xy^-y^3)
=4y^3-8xy^+4x^y-6x^3y+18x^y^-18xy^3+6y^4
3
(a-2b)^2+(a-2b)+1/4
=a^-4ab+4b^+a-2b+1/4