Elimination Method Algebra I?

Subtract the second equation from the first:

-2x+9y=4

9y-2x=4

Then add the original equations:

10x+y=26

10x+y - (9y-2x) = 26-4

8x+8y=22

x+y=22/8=2.75

here is the easy way!!

1. first try to get the x or y the same number

the x is easier so you mult. the 1st eqation by -6 to get 24 and the 2nd one by 4 to get 24

-6(4x+5y=15)

4(6x-4y=11) (neg. 6 because you want the x's to cancel)

2. cross out and add

-24x+5y=15

24x-4y=11

(x cancels) (do 5-4 get 1 so just y) (then 15-11, get 4)

3. so then plug the answer you got for y back into one of the equations (does not matter) and you will get x 9put 4 in all the y values)

4x+5(4)=15

4x+20=15

4x=-5

x= -5/4

x+2y=-5 3x+3y=9 You'll want to get rid of either the x or y by making the coefficients equal. In this case, I'll make the x's equal, i.e. multiply the first equation by 3. Therefore: x(3)+2y(3)=-5(3) 3x + 6y = -15 Once we've done that, you can now get rid of the x but subtracting one equation from the other. (If one of the coefficients are a negative, you must add): 3x+6y =-15 - 3x+3y=9 --------------- 0 + 3y = -24 3y = -24 Now solve for y by making 'y' on it's own (i.e. get rid of the 3): 3y (/3) = -24 (/3) y = -8 You now have the value of -8. So to get the value of x, you can substitute y=-8 into one of the equations at the top. Therefore, when y=-8, x=... x+2y=-5 x+2(-8)=-5 x+-16=-5 x=11 Therefore, y=-8 and x=11

3(4x + 5y = 15)--------->12x + 15y = 45

-2(6x - 4y = 11)--------->-12x + 8y = -22

23y = 23

y = 1

4x + 5(1) = 12

x = 7/4

(3, 7/4)

mutiply the top promblem by 4 the and bottom by 5