3x+y=9,2x+y=1?

substracting equation 2 from 1

we get
3x+y-(2x+y)=9-1
or
3x+y-2x-y=8
or
x=8

substituting the value of x in equation 1
we get
3*8+y=9
or
y=9-24
y=-15

Ok so there are two main methods you could use, substitution or elimination. I think it's always possible to use substitution but not always the easiest. In this case since we have 1y in both equations we can subtract one equation from the other to eliminate the y (Since y-y=0 you get left with only x's on one side and numbers on the other, thus a solution for x).

So if you subtract eqn2 from eqn1 you get:

(3x+y) - (2x+y) = 9-1
3x - 2x + y - y = 8
x = 8

Now you have the value of x you can substitute this in to either of the equations to find what y is. Substituting into equation1:

3(8) + y = 9
24 + y = 9
y = 9 - 24
y = -15

So y= -15 and x = 8.

You can check that these are the solutions for both equations by substituting the values into each equation and seeing if you get LHS = RHS.

Hope it helps (^_^)

subtract equation 2 from 1

hence 3x+y-2x+y=8
hence collect like terms :x=8

therefore 2 x 8+y=1

therefore 16+y=1
therefore y= -15

3x+y=9
3x2+3=9
3x1+6=9
3x3+0=9
there are many possibilties

2x+y=1
2x0+1=1

x = 8
y = -15

set them equal to each other.

3x+y=9 multiply by 2 2x+y=1 multiply by -2

6x+2y=18 elimination
-4x-2y=-2

-2x=16
x=-8

plug x in.

-16+y=1
y=17

3x + y = 9 (solve using substitution)
2x + y = 1

3x + y = 9
y = 9 - 3x

2x + y = 1
2x + (9 - 3x) = 1
2x + 9 - 3x = 1
2x - 3x = 1 - 9
-x = -8
x = -8/-1
x = 8

3x + y = 9
3(8) + y = 9
24 + y = 9
y = 9 - 24
y = -15

∴ x = 8 , y = -15

3x+y=9
2x+y=1
- - -
----------------
x =8
3(8)+y=9
y=9-24
y= -15

x 8
y -15

x = 8 (upon subtraction)

24 + y = 9
y = - 15

x = 8 , y = - 15

3x+y=9
2x+y=1 subtract
-----------
x = 8
then
y = - 15