A quadratic equation is an equation in the form of ax2 + bx + c = 0, where a is not equal to zero.
If a is equal to 0, ax2 + bx + c = 0 becomes bx + c = 0 and bx + c = 0 is not a quadratic equation.
ax2 + bx + c = 0 is called the standard form of a quadratic equation.
A quadratic equation can also be written in vertex form and the vertex form is y = a(x- h)2 + k
Examples of quadratic equations
y = x2 + 6x + 8
y = 3x2 + 12x + 8
y = x2 + 5x + 6
y = (x + 3)2 - 1
y = 3(x + 2)2 + -4
y = (x + 5/2)2 + -1/4