View Full Version : 8x+5y=6 && 3x-2y=10..the elimination method?

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.

. . . . .The 10 is smaller. There's no "rule" about this,

. . . . .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)

Follow this procedure with your examples.

If you get stuck, please reply showing your work. Thank you.

Eliz.

Denis

06-08-2006, 11:33 PM

ok i have nooo idea how to solve these.

pleeaasee help. i have a final in two days

WHY do you have no idea?

WHERE were you when this was taught to your class?

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