Is A=pie r squared linear or non linear how do you know

Question

wondering how to figure out if this equation is linear or non linear

Answer 1

In general the degree of an equation is the highest exponent that is used in it.  Linear equations are those of the form y = mx + b(there are other equivalent formulations) notice that none of the variables (y and x, m and b are constants) are raised to a power greater than 1.

 

A=pi*r^2 is a second degree, or quadratic, equation, because the variable r is raised to the second power.  

Some other ways to see this: use a graphing calculator to make the graphs of the equations.  Linear are straight lines with constant slope, whereas anything with an exponent of more than 1 will be a curve. In the case of quadratics, a parabola.