solve using elimination
9x + 2y = 2
21x + 6y = 4

Question

solve using elimination
9x + 2y = 2
21x + 6y = 4

anonymous · Answer

-3 ( 9x + 2y = 2 )
     21x + 6y = 4

results in 

-18x -6y = -6
  21x +6y = 4

Which you then combined the terms and simplify
-18x + 21x = 3x
-6y + 6y = 0y
-6 + 4 = -2
so we have:
3x +0y = -2
or x=-2/3

Plugging a known x into either equation will lead us to what y equals: 
21(-2/3) + 6y = 4
-14 +6y = 4
6y = 4 +14
6y = 18
y=18/6 = 3
y=3 and x= -2/3

adamaero · Answer

http://pad2.whstatic.com/images/thumb/c/c1/Solve-Systems-of-Algebraic-Equations-Containing-Two-Variables-Step-3Bullet2-Version-2.jpg/670px-Solve-Systems-of-Algebraic-Equations-Containing-Two-Variables-Step-3Bullet2-Version-2.jpg

anonymous · Answer

why did you times it by -3 at the beginning?

texaschic101 · Answer

the reason that you multiplied by a -3 was to eliminate the y's in the problem.

anonymous · Answer

so you just pick a number to illuminate one of them?

anonymous · Answer

Yes, it doesnt matter which equation you multiply nor does it matter which variable you eliminate first.

anonymous · Answer

how do you know what number will illuminate?

raden_zaikaria · Answer

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