Question

Indica la raiz de las siguiente ecuacion (x+1)(2x+5)=5+2×2-5x-12

Answer 1

(x+1)(2x+5) = 5+2×2-5x-12

2x²+5x+2x+5 = 5+4-12-5x

2x²+12x+8 = 0

x² + 6x + 4 = 0

a = 1
b = 6
c = 4

$x = \frac{-b+ \sqrt{ b^{2} -4ac} }{2a}$

o 

$x = \frac{-b- \sqrt{ b^{2}-4ac } }{2a}$

$x = \frac{-6+ \sqrt{ 6^{2}-4(1)(4) } }{2(1)} = \frac{-6+2 \sqrt{5} }{2} = -3+ \sqrt{5}$

entonces las raíces son

$x = -3+ \sqrt{5}$ o $x = -3- \sqrt{5}$