Question

resolva as equações.

$x { }^{2} - 8x + 15$
$x {}^{2} + 3x - 10$
$x {}^{2} - 4x - 12$
$x {}^{2} - x - 90$

Answer 1

A) x² - 8x + 15 = 0

A= 1
B= - 8
C= 15

∆= b² - 4ac

∆= (-8)² - 4 . 1 . 15
∆= 64 - 60
∆= 4

x= - b ± √∆/2a

x= - (-8) ± √4 / 2 . 1
x= 8 ± 2 / 2

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

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

S= ( 5 , 3)

B)x² + 3x - 10 = 0

A= 1
B= 3
C= - 10

∆= 3² - 4 . 1 . (-10)
∆= 9 + 40
∆= 49

x= - 3 ± √49 / 2 . 1
x= - 3 ± 7 / 2

x' = - 3 + 7 / 2 = 4/2 = 2

x''= - 3 - 7 / 2 = - 10 / 2 = - 5

S= ( 2 , -5)