Question

AJUDEM POR FAVOR
RESOLVA AS EQUACOES DE 2 GRAU
1) 2x=15-x² (R: 3, -5)
2) x²+3x-6=-8 (R: -1, -2)
3) x²+x-7=5 (R: -4, 3)
HELP
OBRIGADO.​

Answer 1

1) 2x=15-x² (R: 3, -5)

x² + 2x - 15 = 0

A= 1

B= 2

C= - 15

∆= 2² - 4 • 1 • ( - 15)

∆= 4 + 60

∆= 64

x= - b ± √∆ /2a

x= - 2 ± √64 /2•1

x= - 2 ± 8/2

x'= - 2 + 8/2 = 6/2 = 3

x''= - 2 - 8/2 = - 10/2 = - 5

S= ( 3 , - 5)

2) x²+3x-6=-8 (R: -1, -2)

x² + 3x - 6 + 8 = 0

x² + 3x + 2 = 0

∆= 3² - 4 • 1 • 2

∆= 9 - 8

∆= 1

x= - 3 ± √ 1 /2 • 1

x= - 3 ± 1/2

x'= - 3 + 1/2 = - 2/2 = - 1

x''= - 3 - 1/2 = - 4/2 =- 2

S= ( - 1 , - 2)

3) x²+x-7=5 (R: -4, 3)

x² + x - 7 - 5 = 0

x² + x - 12 = 0

∆= 1² - 4 • 1 • (-12)

∆= 1 + 48

∆= 49

x= - 1 ± √49 / 2 • 1

x= - 1 ± 7 /2

x'= - 1 + 7/2 = 6/2 = 3

x"= - 1 - 7/2 = - 8/2 = -4

S= ( - 4 , 3)