Solving Systems of equasions by elimination?

Question

ok so we have 3 at problems i have to do :
4x + 8y=-30
-4 + 2y-30

x-y=11
2x + y= 19

-6x 5y= 1
6x + 4y=-10

i am SO lost!!! can someone tel me how to do it and the answer please!!
ok thank you!

Answer 1

4x + 8y=-30 -- (1)
-4 + 2y-30 <- i suppose you mean -4x+2y = -30 -- (2)

(1) + (2) you got 10y = -60, so y = -6, x = 9/2

x-y=11 -- (1)
2x + y= 19 -- (2)

(1) +(2) you got 3x = 30, x =10, y =-1

-6x+ 5y= 1 -- (1)
6x + 4y=-10 -- (2)

(1) + (2), you got 9y = -9, y =-1, x =-1

hope this helps

Answer 2

to use elimination you will need to pick one of the variables in each set to get rid of. You would like to have either the x terms or the y terms to have the same coefficient (number)in front of them. take the first set....since the second equation only has a y term and no x term you need to elimnate the y term. to get the coefficients in front of both y terms to be the same you will need to get the 2y to be an 8y like the equation above it. in order to do this you would need to multiply it by 4, so you have to multiply everything in the second equation by that 4 in order for it to stay the same equation. so you would have -16+8y=120 now you can take both equations and subtract one from the other. 4x + 8y = -30
-(0x +8y =136)

you get 4x= -166 and then you get x= -41.5, now plug this back into the first equation where you see x at and solve it for y. 4(-41.5) + 8y= -30
-166+8y= -30
8y= 136
y=17


now do the second set....notice both y terms have a 1 as the coefficient. so you dont need to multiply by anything. simply add the two equations.

x - y = 11
+2x + y = 19


you get 3x = 30 then solve for x and get x=10. now since x is in both of those equations just plug the value you got of 10 into one of them and solve for y. such as 10 - y =11
- y = 1
y= -1

and the third is easy too. both x terms have same coefficient already so just add the equations again.

-6x + 5y = 1
+ 6x + 4y = -10

you get 9y= -9
y= -1

now pick either equation again and use this value for y and plug it into one of them. take first one -6x + 5(-1) =1
-6x + -5= 1
-6x = 6
x= -1


hope this is clear and helps you out.

Answer 3

There was some few errors in your equation so i'm guessing their the answers that i have for you. i hope them are correct. :D

the first problem: x = 7.5 y = 30
the second problem: x = 10 y= -1
and the last problem: x= 7.6 y = 9

This problem is pretty easy all you have to do is chop the equation into piece by piece
1st pick one letter to start off with (y or x)
2nd get that letter that you chosed by it self
for example: x-y=11
y= -x+ 11
3nd take that equation you just did and replace it with the y in the other equation.
For example: 2x +(-x +11)=19
4th solve the equation for example
2x +(-x +11) =19
3x +11=19
3x=30
x=10
5th now solve for your other letter by the one you just found out. Use one of the equation in this problem though
Example : 2x + y=19
2(10)+ y = 19
20 + y = 19
y = -1

There u have your answer i hope this helped you

Answer 4

Question 1
I am guessing that question is as below,but it is method that is important.
4x + 8y = - 30
-4x + 2y = - 30--------Add
10y = - 60
y = - 6
4x - 48 = - 30
4x = 18
x = 18 / 4 = 9 / 2

Question 2
3x = 30 (after adding)
x = 10
10 - y = 11
y = - 1
x = 10 , y = - 1

Question 3
9y = - 9 (after adding)
y = - 1
6x - 4 = - 10
6x = - 6
x = - 1
x = - 1, y = - 1

Answer 5

1)4x + 8y=-30 ------------------[1]
-4x + 2y=-30-----------------------(2)
from (1)+(2)
10y=-60
y=-6
putting y=-6 in (1)
4x-8*6=-30
or, x=18/4
x=9/2

the remaining two are the same