a) (x+2) (y+1) b) (2x-1) (y-3) c) (a+1) (a+2) d) (2x+1) (1-3x) e) (2x^4-y) (x^4+y)
źródło:
a) (x+2)(y+1)=xy+x+2y+2 b) (2x-1)(y-3)=2xy-6x-y-3 c) (a+1)(a+2)=a^2+2a+a+2=a^2+3a+2 d) (2x+1)(1-3x)=2x-6x^2+1-3x=-6x^2-x+1 e) (2x^4-y) (x^4+y)=2x^8+2x^4y-x^4y-y^2