Question

Parabola y=x²+bx+c memotong sumbu x dititik ( 1,0 ) dan ( 5,0 ). persamaan sumbu simetrinya adalah....

Answer 1

Para bola memotong di(1,0) dan (5,0)
x1= 1
x2 = 5
sumbu simetri x= 1/2 (x1+ x2) = 1/2 (1+ 5)= 1/2 (6) =  3

cara lain
y = x² + bx + c
(1,0) => 1 + b + c = 0 --> b+c = -1
(5,0) => 25+ 5b + c = 0 --> 5b + c = - 25

b+ c  = -1
5b + c =  - 25
----------------(-)
-4b =  24
b = -6

sumbu simetri  x  = -b/2a  = - (-6)/2 = 3