Under what conditions would you use graphing, elimination, and substitution?

We solve  equations by the method of graphing or by
solving.

The method of solution is our choice. Graphing
helps our visual grasp. But accuracy requires solving of the
equations.

The linear equations of one variable does not
require substitution or elimination. We solve linear equation of one variable and one
single equation by isolation of the unknown or variable to one side and knowns or
numbers to the other side. The type of operations we do is (i) adding or subtracting
equals to both sides, (ii) multiplying or dividing both sides by equals.
But never multiply or divide by zeros thinking that zeros are
equals.

In solving equations with two or
more variables we are dealing with more than one equations. Here we can use the technic
of reducing the number of variables and the number of equtions either by elimination or
substitution till we arrive at a single equation with a single
variable.