Hydrogen is the only element where the isotopes are given specific names. Common hydrogen, which has zero neutrons, is called protium. Hydrogen with one neutron is called deuterium and hydrogen with two neutrons is called tritium. See the picture at the top of the page.
The following steps can be used as a guide as you read through the examples for using the substitution method. Steps for Using the Substitution Method in order to Solve Systems of Equations. 1  Solve 1 equation for 1 variable. ( 2 Put in y = or x = form). 3  Substitute this expression into the other equation and solve for the missing variable. 4  Substitute your answer into the first equation and solve.
Substitution is best used when one (or both) of the equations is already solved for one of the variables. It also works well if one of the variables has a coefficient of 1. Elimination: Elimination is the method that I use almost every time. If you are not sure which method to use, I recommend that you use elimination. Elimination is best used when both equations are in standard form (Ax + By = C). Elimination is also the best method to use if all of the variables have a coefficient other than 1. I hope this gives you some idea about which method you should use. All three methods will give the same solution. Also, you should always check your answer in both equations to make sure it is correct.