Quadratic Forms

What are Quadratic Forms?

Quadratic forms contain a variable such as the x2 term as their highest power.

There are various quadratic forms.

To view the free examples, please scroll down to the next section.

Quadratic Forms – Types

Type 1:   ax2 + bx + c = 0


The “standard” quadratic form is  ax2 + bx + c = 0

In the equation above, a, b, and c are positive or negative numbers.

a, b, and c can also be fractions or imaginary numbers.

So, 2x2 + 5x – 3 = 0 is an example of this quadratic form.

Note that the variable a can never be equal to zero in the quadratic form.

3x + 2 = o is not a quadratic because none of the terms are raised to the power or 2.

The standard quadratic form can be rewritten as other equations such as:

ax2 = bx + c

ax2 + bx = c

ax2 + c = bx

Type 2:   x2 + bx + c = 0

When a = 1, we can write the equation as follows:  x2 + bx + c = 0

So, x2 + 5x + 6 = 0 is an example of this quadratic form.

As mentioned above, the variable a can never be equal to zero in the quadratic form.

Type 3:  (ax + b)(x + c) = 0

The factored form of the equation is as follows: (ax + b)(x + c) = 0

An example of this form is: (x + 1)(x – 5) = 0

Type 4:  x2 + bx = 0

When c = 0, the quadratic form can be written as shown below:

x2 + bx = 0

x2 – 10x = 0 is an example of this quadratic form.

Type 5:   x2 = n


When b = 0 and c = 0, the quadratic form can be written as shown below:

x2 = 4

If you wish to solve for x in the above questions, you should also see our posts on the quadratic formula and solving quadratic equations.