4)(4-3d+2d^2)(1-7d)= 4-28d-3d+21d^2+2d^2-14d^3 = 4-28d-3d+23d^2-14d^3 = -14d^3+23d^2-31d+4
1) (ab+7)(8-ab)= 8ab-a^2b^2+56-7ab= ab - a^2b^2+56
2) (xy+11)(xy-12)= x^2y^2 -12xy+11xy-132=x^2y^2-xy-132
3) (1,5-6nm)(8nm+2,5) = (1,5-6mn)(8mn+2,5) = 12mn+3,75-48m^2n^2-15mn = -3mn+3,75-48m^2n^2
4) (9st-1.6)(10+1,8st) = 90st+16,2s^2t^2-16-2,88st = 87,12st+16s^2t^2-16