Question

x2+x-30=0
e
x2-5x-6=0
??

Answer 1

A) x² + x - 30 = 0

A= 1
B= 1
C= - 30

∆= b² - 4ac

∆= 1² - 4 . 1 . (-30)
∆= 1 + 120
∆= 121

x= - b ± √∆ / 2a

x= - 1 ± √ 121 / 2 . 1
x= - 1 ± 11 / 2

x'= - 1 + 11 / 2= 10 / 2 = 5
x''= - 1 - 11 / 2 = - 12 / 2 = - 6

S= ( 5 , - 6)

B) x² - 5x - 6 = 0

A= 1
B= - 5
C= - 6

∆= b² - 4ac

∆= ( - 5)² - 4 . 1 . (-6)
∆= 25 + 24
∆= 49

x= - b ± √∆ / 2a

x= - (-5) ± √ 49 / 2 . 1
x= 5 ± 7 / 2

x' = 5 + 7 / 2 = 12 / 2 = 6
x'' = 5 - 7 / 2 = - 2 / 2 = - 1

S= ( 6 , - 1)