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06-08-2006, 08:48 PM
ok i have nooo idea how to solve these.

solve each system using the elmination method.
8x+5y=6
3x-2y=10

-3x+8y=10
5x+y=80

pleeaasee help. i have a final in two days

stapel
06-08-2006, 09:00 PM
In general, "elimination" (or "addition") means to find some way to eliminate a variable. This is customarily done by multiplying one or another equation by some value, and then adding down. For instance:

. . . . .Solve the following by elimination:
. . . . . . .5x - 6y = -3
. . . . . . .2x - 5y = 4

. . . . .The smallest common multiple of 6 and 5 is 30.
. . . . .The smallest common multiple of 5 and 2 is 10.
. . . . .but smaller numbers are usually easier, so:

. . . . .. . .2[5x - 6y = -3]
. . . . . . .-5[2x - 5y = 4]

. . . . . . . .10x - 12y = -6
. . . . . . .-10x + 25y = -20

. . . . .Add down to get:

. . . . . . .13y = -26
. . . . . . . . .y = -2

. . . . .Then:

. . . . . . .2x - 5(-2) = 4
. . . .. . . . .2x + 10 = 4
. . . . . . . . . .. . .2x = -6
. . . . . . . . . . .. . .x = -3

. . . . .Solution: (x, y) = (-3, -2)