Question

use the elimination method to figure the systems of equations:


5u+2v=-17 *1
3u+v=-5 *2

5u+2v=-17
6u+2v=10 use elimination

11u=-7 divide both sides by 11
u=-7/11??

then plug in to first formula and got if u =-7/11
5(-7/11)-2v=-17
35/11+2y=-17 which we have to divide both by 35/11

which gives me 2v=-17 divide by 35/11 and i get hella lost

Answer 1

You should have gotten this

5u + 2v = -17
-6u - 2v = 10

-u = -7
7 = u

Answer 2

ok so if I change to a 7. Still stuck u=-7/11??

then plug in to first formula and got if u =7/11
5(7/11)-2v=-17
35/11+2y=-17 which we have to divide both by 35/11

which gives me 2v=-17 divide by 35/11 and i get hella lost

Answer 3

srbbw44,

You made one small error when multiplying the second equation times 2. you should have gotten:

5u+2v=-17
6u+2v=-10 use elimination

Not
6u+2v=10

Solve with those two.

Answer 4

so would that make my -7

Answer 5

so u would get 11u=-27

Answer 6

divide both sides by 11 to get a crazy problem
2v=-17 divide that by 135/11

Answer 7

If you add the equations like that you would get

11u+4v=-27

You need to eliminate one variable.

Answer 8

Yeah, don't pay attention to anything I did

Answer 9

Subtract one equation from the other to eliminate the v variable and then solve for u.

Answer 10

hero i messed up the equation not u

Answer 11

I get either -u = -7 or u = 7 depending on which equation you subtract from the other. I think you did this correctly, Hero.

Answer 12

or am I missing the sarcasm ;o)

Answer 13

no ideal i can plug the u=-7 v= 9 but it fits in the first equation but not the second one when we check our math from our origanal problem

Answer 14

I don't get u = -7

Begin with:
5u + 2v = -17
6u + 2v = -10

Subtract the 2nd from the 1srt equation:
5u + 2v = -17
-(6u + 2v = -10)

Use distributive property:
5u + 2v = -17
-1(6u + 2v) = -1(-10)

Written out:
5u + 2v = -17
-6u + -2v = 10

Yields:
-u = -7

Meaning:
u = 7

Substitute that into both equations. I het the same value in each with u = 7 solving for v.

You?

Answer 15

The long way I wrote it is my usual way of doing these because when I make an error, it is almost always that I missed a sign.