Question

15. Calculaţi:
a) (x + 1)(x + 2);
c) (2x - 3)(1 - x);
b) (x - 1)(x + 2);
d) (3x + 1)(2x - 3).
​

Answer 1

a)(x+1)(x+2)=x×x+2x+x+2=x²+2x+x+2=x²+3x+2

c)(2x-3)(1-x)=2x-2x×x-3-3(-x)=2x-2x²-3+3x=5x-2x²-3=-2x²+5x-3

b)(x-1)(x+2)=x×x+2x-x-2=x²+2x-x-2=x²+x-2

d)(3x+1)(2x-3)=6x×2x-3x×3+2x-3=6x²-9x+2x-3=6x²-7x-3