How do you use the elimination method to solve -4x + y= -8 and x - 4y= -7?

Answer 1

u should solve for either x or y and substitute it in for the other equation.

Ex.
If -4x + y= -8 then it is same as --> y= -8 +4x (here i solved for y alone)
Next i sub it in the 2nd equation

x - 4y = -7 , recall that y = -8 +4x
So:
x - 4(-8 +4x) = -7 --> x +32 -16x = -7 --> 32-15x=-7

Then i solve for x
32-15x=-7
-15x=-39
x=-39/-15 = 13/5

Now that u have the exact value for x u can solve for y using any equation as u wish try it out........u should get y = 12/5

if u use matrices then
[-4,1;1,4] -->a [-8;-7]-->c [x;y]-->b

a*b=c

a^(-1)*c = b = [13/5;12/5]

Answer 2

first find what variable you want to eliminate, x or y. I think I'm going to eliminate x, in honor of my cat Xerxes (jk). I like to put the equations on top of each other cuz i'm visual like that.

-4x + y = -8
(x - 4y = -7) 4

in order to eliminate x u have to multiply the bottom equation by 4.

-4x + y = -8
4x - 16y = -28

Then u add the two equations. see that the -4x on top eliminates the positive 4x on the bottom. So after adding u get:

-15y = -36

then you divide each side by -15 to get y = 2.4

Now you just plug in 2.4 for y and solve for x. (i got x = 2.6, i might be wrong so check)

Answer 3

-4x + y = -8
y = 4x - 8

x - 4y = -7
x - 4(4x - 8) = -7
x - 16x + 32 = -7
-15x = -39
x = 39/15
x = 13/5

two & three-fifths

Answer 4

- 4x + y = - 8
x - 4y = - 7
4x - 16y = - 28
- 15y = - 36
y = 2.4
x - 9.6 = - 7
x = 2.6

- 4*2.6 + 2.4 =? - 8
- 10.4 + 2.4 = - 8

Answer 5

you should really read you math book and the notes you took in class.