What is the difference between a defined and an undefined term in geometry?

An undefined term in geometry means that such terms cannot be explained properly. The examples of undefined terms in geometry are point, line, and plane. A point is a dimensionless term, which has no length or width or thickness. Similarly a line or a plane also has no width. A line can be extended in two directions, while a plane can be extended in all directions.

On the other hand undefined terms combines in a meaningful way, i.e. when a line crosses another lines, it forms an angle. Thus angle is a defined term in geometry.  

i think it's ф or x=6,-6

step-by-step explanation:

-x^2=-36

x^2=-36

ф

or

if you mean by : -(x^2)=-36

it'll be: x^2=36

x=6,x=-6

hope it'll ! have a good day!

you for asking!