Odpowiedź:
a) (x+1)(x+2)= x^2+2x+x+2= x^2+3x+2
b) (3a+4)(a-5)= 3a^2-15a+4a-20= 3a^2-11a-20
c) (2t+1)(1-3t)= 2t-6t^2+1-3t= 6t^2-t+1
d) (3ab-7)(3-7ab)= 9ab-21a^2b^2-21+49ab=
= 58ab-21a^2 b^2-21
e) (-x+y)(5x+6y)= -5x^2-6xy+5xy+6y^2= -5x^2-xy+6y^2
f) (x+5y)(7x-y)= 7x^2-xy+35xy-5y^2= 7x^2+34xy-5y^2
g) (2x-y)(x+y)= 2x^2+2xy-xy-y^2= 2x^2+xy-y^2
h) (ab-a)(2ab+6a)= 2a^2 b^2+6a^2 b-2a^2 b-6a^2=
= 2a^2 b^2-4a^2 b-6a^2
