Question

Calculati:
a) (x-7)(x+3)-(x+1)(x+2)+(5-x)(x-4)
b) (a-b)(a+3b)+(2a-b)(a+2b)-(a+b)(a-2b)
c) (2-x)(x+x²)-x²(3+x)+8+(x+2)(5+x²).

Answer 1

a) (x-7)(x+3)-(x+1)(x+2)+(5-x)(x-4)
Se inmultesc pe rand fiecare termen din paranteze.
(x-7)(x+3)= x^2 + 3x - 7x -21=x^2 -4x -21
(x+1)(x+2)= x^2 + 2x + x + 2=x^2 + 3x +2
(5-x)(x-4)= 5x -20 - x^2 + 4x = -x^2 + 9x - 20

(x-7)(x+3) - (x+1)(x+2) + (5-x)(x-4) = x^2 -4x - 21 - (x^2 + 3x +2) + (-x^2) + 9x -20= x^2 - 4x -21 - x^2 - 3x - 2 - x^2 + 9x - 20 = -x^2 + 2x - 43


Sper ca ai inteles ce am facut.