Answer:
[tex]x =\pm\sqrt{\dfrac{y-c}a}[/tex]
Step-by-step explanation:
[tex]~~~~~~y= ax^2 +c\\\\\implies ax^2 = y-c\\\\\implies x^2 =\dfrac{y-c}{a}\\\\\implies x =\pm\sqrt{\dfrac{y-c}a}[/tex]