posted by Amanda on .
1. Explain the advantages and disadvantages of both the substitution method and the elimination method for solving a system.
Help please. The only reasons I can think of is because in substitution it might be more difficult cause there's a possibility of working with fractions.
Actually, that is the best reason.
I use the following criterium.
If I see one of the variables having a coefficient of 1 OR -1, I solve for that variable and use substitution, resulting in no fractions, unless the equation contains fractions to begin with.
As a matter of fact if I see fractions in either one of my equations, I usually multiply each term by the LCD of the fractions, thereby eliminating the fractions.
g. 4x+5y = 12
3x-y = 9
I would solve for y in the second, then sub that into the first.
Of course if the answer itself is a fraction you would be stuck with thAT.