Question

1) Sa se descompuna:
a) x²+7x=12=
b) x²+8x+12=
c) x²-3x-28=
d) x²+6x+8=
e) x²-4x-12=

Answer 1

a) trebuie sa aplici regula : 2 numere care adunate sa dea 7 si inmultite 12...in cazul punctului a)
$x^{2} +7x+12= x^{2} +4x+3x+12=x(x+4)+3(x+4) \\ =(x+4)(x+3)$
B)$x^{2} +8x+12= x^{2} +6x+2x+12=x(x+6)+2(x+6)= \\ =(x+6)(x+2)$
c)$x^{2} -3x-28= x^{2} -7x+4x-28=x(x-7)+4(x-7) \\ =(x-7)(x+4)$
d)$x^{2} +6x+8= x^{2} +4x+2x+8=x(x+4)+2(x+4)=(x+4)(x+2)$
e)$x^{2} -4x-12= x^{2} -6x+2x-12=x(x-6)+2(x-6) \\ =(x-6)(x+2)$