Name: matthew Question: simultanious equations question what is 4x + y = 4 2x - 3y = 5 what is x and y looks impossible... cheers Hi Matthew, You have two equations in two unknowns, x and y, and the standard way to approach such problems is to "eliminate one of the unknowns" and change the problem to one involving a single equation in one unknown. I can see two ways to approach this particular problem, eliminate x or eliminate y. Eliminate x The first step is to manipulate the equations so that the coefficients of x in the two equations are the same. You can do this by muliplying both sides of the second equation by 2. This gives 4x + y = 4 4x - 6y = 10 Subtracting the second equation from the first results in (4x + y) - (4x - 6y) = 4 - 10 or 7y = -6 Hence y = -6/7 and substitution into either of the two equations you started with will yield x. Eliminate y If you multiply both sides of the first equation by 3 you can eliminate y. Thus 12x + 3y = 12 2x - 3y = 5 and adding the two equations yields (12x + 3y) + (2x - 3y) = 12 + 5 or 14x = 17 Hence x = 17/14 and substitution will yield y. I hope this helps, Penny Go to Math Central