Question

X2-8x +15=0
(a) S = 2 e 3
(b) S = 3 e 5
(c) S = 4 e 5
(d) S = 1 e 2

preciso urgente por favor ​

Answer 1

Resposta:

(b) S = 3 e 5

Explicação passo-a-passo:

x

2

−8x+15=0

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

2∗a

−b±

−b

2

−4∗a∗c

a=1b=−8c=15

Vamos encontrar o Δ:

Δ=b2−4ac

Δ=(−8)2−4*(1)*(15)

Δ=64−60

Δ=4

\begin{gathered}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 \end{gathered}

x=

2∗a

−b±

△

x=

2∗1

−(−8)±

4

x=

2

8±2

x

′

=

2

8+2

x

′

=

2

10

x

′

=5

x

′′

=

2

8−2

x

′

=

2

6

x

′′

=3

S = \left \{ 3, 5 } \right. \}