axa de simetrie este x varf = - b /2a
f(x) = 5x² + 3
x = - 0 / 2 ·5 = 0 axa x = 0
f(x) = x² - 4
x = 0 axa x = 0
f(x) = - 3 (x² + 4x + 4 ) = - 3x² - 12x - 12
x = - ( -12) / 2· ( -3) = - 2 axa x = -2
f(x) = 6x² - x + 3
x = - ( -1) / 2·6 = 1 /12 axa x = 1 /12