Question

 resolver esta equação x²-8x+15=0

Answer 1

x¹= 8+2 = 10 =5
        2       2

 x duas linhas = 8-2 = 6 = 3
                          2     2

Answer 2

$x^{2} -8x + 15 = 0$

$\frac{-b \pm \sqrt{-b^2 -4*a*c}}{2*a}$

a=1b=−8c=15
Vamos encontrar o  Δ:

Δ=b2−4ac
Δ=(−8)2−4*(1)*(15)
Δ=64−60
Δ=4

$x = \frac{-b \pm \sqrt{\triangle}}{2*a} \\ \\x = \frac{-(-8) \pm \sqrt{4}}{2*1} \\ \\ x = \frac{8 \pm2}{2} \\ \\ x' = \frac{8 +2}{2} \\ \\ x' = \frac{10}{2} \\ \\ x' = 5 \\ \\ \\ x ''= \frac{8 -2}{2} \\ \\ x' = \frac{6}{2} \\ \\ x'' = 3$

S = $\left \{ 3, 5 } \right. \}$