+ + 7 Efectuați: a (x - 3)(x + 2) + (2x + 1)(3x - 2) - 2x(x + 1); b (x-6)(2x + 5) - (x + 2)(x + 3) + (3 - x)(x + 4); c (x2 + x)(x + 1) - x(2 + x) + (x + 2)(3 + x2) - 6; d (x2 + 2x)(x + 3) + 2x(x2-x-1)-(3x - 1)(x - x); e (3x + 1)(x2 + 2x - 5) - (x + 2)(2x2 - x + 3); f(x - 4)(2x2 + x + 3) + (3x - 2)(x - 5x + 19). + ma puteti ajuta?​