What is a quadratic equation ? Definition and examples.


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

Standard form

y = x2 + 6x + 8

y = 3x2 + 12x + 8

y = x2 + 5x + 6

Vertex form

y = (x + 3)2 - 1

y = 3(x + 2)2 + -4

y = (x + 5/2)2 + -1/4

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