Question

Ofer 55 de puncte.Calculati
$(2x + 1) {}^{2} - (2x + 3)(2x - 3) + x + 1 = 7(2x - 4) - 51$
​

Answer 1

Salut!

(2x+1)²-(2x+3)(2x-3)+x+1=7(2x-4)-51

Observam ca avem doua formule de calcul precurtat. Pentru a fi siguri ca nu gresim, le luam separat si apoi le introducem inapoi in exercitiu.

(2x+1)²=(2x)²+2*2x*1+1²=4x²+4x+1

(2x+3)(2x-3)=(2x)²-3²=4x²-9

Acum continuam exercitiul:

(2x+1)²-(2x+3)(2x-3)+x+1=7(2x-4)-51

4x²+4x+1-(4x²-9)+x+1=14x-28-51

4x²+4x+1-4x²+9+x+1=14x-79

5x+11=14x-79

11+79=14x-5x

90=9x

x=90:9

x=10

Succes!