Question

7x²-2x-5=0 me ajudem ..

Answer 1

Ingridvrb,

$7x^2 - 2x - 5 = 0$

$a = 7$
$b = -2$
$c = -5$

Usando a fórmula de Bháskara:

$\Delta = b^2 - 4.a.c$
$\Delta = (-2)^2 - 4.7.(-5)$
$\Delta = 4 + 140$
$\Delta = 144$

Como Δ > 0, usamos:

$x = \frac{-b +- \sqrt{\Delta} }{2.a}$

$x = \frac{-(-2) +- 12}{2.2}$

$x = \frac{2 +- 12}{4}$

Calculando x' e x'':

$x' = \frac{2+12}{2} = \frac{14}{2} = 7$

$x'' = \frac{2-12}{2} = \frac{-10}{2} = -5$

Portanto:

$\boxed{\boxed{S = \{7, -5\}}}$

Answer 2

$7 x^{2} -2x-5=0$
Δ=$(-2) ^{2}-4.7.(-5)$
Δ=$4+140$
Δ=$144$
....................
$x= \frac{+2 +- \sqrt{144} }{2.7}$
$x= \frac{+2 +- 12}{14}$
$x1= \frac{+2 +12}{14} = \frac{14}{14} = 1$$x2= \frac{+2-12}{14} = \frac{-10}{14} = \frac{-5}{7}$