Question

Descompuneti intr-un produs de doi factori expresia 2x la puterea 2 - x- 1.

Answer 1

$2x^2-x-1=2x^2-2x+x-1$
$2x^2-2x+x-1=2x(x-1)+1(x-1)=(2x+1)(x-1)$

Answer 2

2x²-x-1

a=2
b=-1
c=-1
Δ=b²-4ac=1-4·2·(-1)=1+8=9
prima solutie x = (-b+√Δ)/2a = (1+3)/2·2 = 4/4=1
a doua solutie x = (-b-√Δ)/2a = (1-3)/2·2 = -2/4=-1/2

Descompunerea:
2x²-x-1 = 2(x-1)(x+1/2) = (x-1)(2x+1)