(y-8)*(2y-1)
(3y+1)*(5y-2)
(3x+4y)*(4y-3x)

(Y-8)*(2Y-1)=2Y^2-Y-16Y+8=2Y^2-17Y+8(3Y+1)*(5Y-2)=15Y^2-6Y+5Y-2=15Y^2-y-2(3x+4y)*(4y-3x)=12x*y-9x^2+16y^2-12x*y=16y^2-9x^2