Question

rezolvati in R ecuatiile :
a) x²-7x+6=0
d) x²-8x-20=0

Answer 1

$a) {x}^{2} - 7x + 6 = 0$

${x}^{2} - 6x - x + 6 = 0$

$x(x - 6) - (x - 6) = 0$

$(x - 6)(x - 1) = 0$

$x - 6 = 0 = > x = 6 \: \in \: \mathbb{R}$

$x - 1 = 0 = > x = 1 \: \in \: \mathbb{R}$

$b) {x}^{2} - 8x - 20 = 0$

${x}^{2} - 10x + 2x - 20 = 0$

$x(x - 10) + 2(x - 10) = 0$

$(x - 10)(x + 2) = 0$

$x - 10 = 0 = > x = 10 \: \in \: \mathbb{R}$

$x + 2 = 0 = > x = - 2 \: \in \: \mathbb{R}$