Solving three linear equations

[nkp]

Hi!

When I see a problem with two linear equations and two variables, I can solve for each variable (given that the equations are not the same).

Can the same be said when solving for three linear equations?

[RonPurewal]

Hi!

When I see a problem with two linear equations and two variables, I can solve for each variable (given that the equations are not the same).

you should be careful with this.
there are numerous exceptions to this principle... and, if this sort of thing shows up in data sufficiency, it's virtually guaranteed that the problem will test the exceptions, NOT the 'usual' principle.

for instance, if you're restricted to whole numbers (= non-negative integers), all of the usual algebraic principles are out the window (since algebra doesn't have any tools for distinguishing whole numbers from non-whole numbers).

try these:
• 5x + 7y = 47: this equation has two different solutions in whole numbers.
• 5x + 7y = 48: this equation has only one solution in whole numbers.

[RonPurewal]

Can the same be said when solving for three linear equations?

most of the time yes... but this is completely, totally, and absolutely irrelevant to this exam. this exam will NEVER give you 'busy work'—and solving a three-equation system would most certainly qualify as 'busy work'.

in the unlikely event that you ARE presented with three equations (or three inequalities, or whatever), there should be some one-step process that you can do with them.
e.g., you may just be able to add them all together.

[nkp]

Great, thank you!

[RonPurewal]

you're welcome.