Question 73446
ow can we get an answer to Solving systems of equations using elimination, such as the one below
2x + 5y = -1
 x + 2y = 0
:
When you use the "elimination method", we multiply 1 or both equations so that
when we add or subtract the two equations, one of the unknowns is eliminated.
:
Multiply the 2nd equation by 2, and subtract from the 1st equation:
2x + 5y = -1
2x + 4y = 0
-------------- subtracting, eliminates x
0x + 1y = -1
:
Therefore we know y = -1
:
Find x by substituting -1 for y in the 1st equation:
2x + 5(-1) = -1
2x - 5 = -1
2x = -1 + 5; added 5 to both sides
2x = +4
x = 4/2; divided both sides by 2
x = 2
:
Check for equality by substituting both solutions in the 2nd equation:
2 + 2(-1) = 0
2 - 2 = 0; proves our solutions are right
:
Do you think you will be able to do this now? Any questions?