Question

equaçao do 2° grau
a) x²-4x-5=0​

Answer 1

x² - 4x - 5 = 0

a= 1

b= -4

c= -5

∆= b²-4•a•c

∆= (-4)²-4•1•(-5)

∆= 16+20

∆= 36

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

$\frac{x \: = \: - ( - 4) \frac{ + }{ - } \sqrt{36} }{2.1}$

$\frac{x \: = \: 4 \frac{ + }{ - }6 }{2}$

X' = (4+6) ÷ 2

X' = 10 ÷ 2

X' = 5

X" = (4-6) ÷ 2

X" = -2 ÷ 2

X" = -1

S{5, -1}