Question

A soma das raizes da função y= (x+11) (x-8) é:

A) -19
B) 19
C) 3
D) -3
E) 2

Answer 1

y = (x + 11).(x - 8)
0 = (x + 11).(x - 8)

(x + 11).(x - 8) = 0

x + 11 = 0
x = - 11

x - 8 = 0
x = 8

S = - 11 + 8 
S = - 3

Resp.: d ) - 3

*********************************************
(x + 11).(x - 8) = 0
x² - 8x + 11x - 88 = 0
x² + 3x - 88 = 0
a = 1; b = 3; c = - 88

S = -  b      =  -  3       =   - 3
       -------       -------
          a              1

S = - 3