A **linear term** has a degree of 1. For example, 5x, -2x and x are all linear terms. These terms are x to the first degree (X^{1}), where the “1” isn’t written (because any number to the first power is just that number).

Terms that are *not *linear are called **non-linear terms.** The most common one you’ll come across in calculus is the quadratic term.

## Quadratic Term, Linear Term and Constant Term

A quadratic equation has the form f(x) = ax^{2} + bx + c, which contains three terms:

- ax
^{2}= the quadratic term, - bx = the
**linear term**, - c = the constant term.

For example, for the function f(x) = 9x^{2} + 3x – 5, the linear term is 3x.

Not all quadratic functions have linear terms. For example, 10x^{2} – 5 = 0.

## Coefficient of Linear Terms

The “3” in the above equation is the coefficient , and the “x” is the variable.

It’s possible to have more than one coefficient of a linear term. For example, the coefficient here:

f(x) = 9x^{2} + 3bx – 5

is 3b.

## How It Affects the Shape of Parabolas

Changing the linear term affects the vertex position, both horizontally (along the x-axis) and vertically (along the y-axis).

Increasing “b” moves the parabola down and to the left:

Decreasing “b” moves the parabola down and to the right:

This may come as a surprise: decreasing “b” moves the graph towards the positive direction on the x-axis, and increasing it will move it in the negative x-direction.

## References

Graphing calculator on Desmos.

Quadratic Functions. Retrieved November 5, 2019 from: https://math.dartmouth.edu/opencalc2/cole/lecture3.pdf