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.
Identify a condition of one or both of the equations that might persuade you to use either the elimination method or the substitution method. Possible answer: If both equations share a common term, use the elimination method.