Solve each Linear system?

Question

x + y = -8
x - 2y = 7

Answer 1

[17]
x+y= -8.........(1)
x-2y=7..........(2)
subtracting (2) from (1)
3y= -15
y= -15/3= -5
Plugging y in eqn (1)
x-5= -8
x= -8+5= -3

Answer 2

Putting x = -8-y in x - 2y = 7

-8-y-2y = 7

-3y = 7+8

-3y = 15

y = -5

putting y = -5 in x-2y = 7

x-2*(-5) = 7

x+10 = 7

x = 7-10 = -3

Answer 3

x + y = -8........(1)
x-2y=7............(2)
from (2), x-2y=7
x=7+2y....(3)
sub 3 into 1,
7+2y+y=-8
7+3y=-8
3y=-15
y=-5

when y=-5,
x+(-5)=-8
x=-3

hence, y=-5, x=-3.
Happy Mathematic'ing

Answer 4

you could use elimination method:
eq.1 x+y=-8 ; eq. 2 x-2y=7
like this:multiply eq. 2 by -1 so that you could cancel

x+y=-8
-1 (x-2y = 7) -1

then: cancel the x's and add the remaining terms in the two equations

so: 3y= -15
evaluate:
y=-5

then substitute to eq. 1:
x+(-5)=-8

evaluate:
x= -3

Answer 5

x + y = - 8
x - 2y = 7
Eliminating x,
- x - y = 8
x - 2y = 7

- 3y = 15
y = - 5

x - 5 = - 8
x = - 3

Answer 6

x+y= -8 <---- solve for x
x-2y= 7

x= -8-y <---- Sub into second equation

(-8-y)-2y=7
-3y=15
y=-5 <----sub into either of the starting equations

x-5=-8
x=-3

Solution: (-3,-5)

Check:
-3+(-5)=8
-3-5=-8
-8=-8 :)

Answer 7

lets name x+y = -8 as eq. 1 and x-2y = 7 as eq. 2

by substitution method we have to solve for y or x..i choose to solve for y then we have

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

substitute this result to eq 2..then we have,

x - 2 (-8-x) = 7
x + 16+ 2x = 7
3x = 7-16
x = - 9/3
x = -3

then for y we have

y = -8 - (-3)
y = -8 + 3
y = -5

the ans is x = -3 and y = -5

Answer 8

x=-3
y=-5