how do u do the linear system 3x-y=2,y=2x-9 using substitution?

Answer 1

Pick one to solve for. As you have y already solved for, I did it with that first, but it works to do it the other way as well.

So, insert the y = 2x - 9 into the other equation.

3x - (2x - 9) = 2
3x - 2x + 9 =2
x +9 =2
x = -7

Then plug that into the other equation to figure out what y is

y = 2(-7) - 9
y = -14 - 9
y = -23

Then plug your answers back into the first equation, to make sure that it checks out.

So your answer is
(-7, -23)


BTW, the person right above me did not distribute the negative into the entire parentheses in this step: 3x - (2x - 9) = 2, which is why their answer differs from mine, but if you plug their numbers back in, you can see that the numbers don't check out

Answer 2

u put the y=2x-9 into the 3x-y=2
so then you would have

3x-(2x-9)=2
3x-2x+9=2
x+9=2
x=-7

then you replace x with your answer -7 which would look like this-

y=2(-7)-9
y=-14-9
y= -23

so your final answer would be (-7, -23)

hope I'm right and I hope this helps!
have a good day!

Answer 3

sub for one of them, do y first.
3x - (2x - 9) = 2
3x - 2x - 9 = 2
x - 9 = 2
x = 11

sub for x
y = 2(11) -9
y = 22 - 9
y = 13

Hope I showed enough work to show you how to do it.

Answer 4

only in 6th grade but i can try.
3x-y=2
+ y=2x-9
--------------------
3x = 2x-7
x = -7
hopefully that helps

Answer 5

combine like terms , then isolate the variable , multiply or divide , then solve ..Good luck