Question

solve system using substitution
x=2y-1
2x-y=4

Answer 1

We can substitute '2y - 1' for 'x' in the 2nd equation:

2x - y = 4

2(2y - 1) - y = 4

Distribute 2 into the parenthesis:

4y - 2 - y = 4

Combine like terms, can you subtract 4y - y?

Answer 2

4y - 1y

It's the same thing as 4 - 1, but we put a 'y' next to it.

For example:

23x - 14x = 9x, because 23 - 14 = 9.

Answer 3

3y?

Answer 4

Yes!

So we have:

\(3y - 2 = 4\)

Now add 2 to both sides, what's 4 + 2?

Answer 5

3y=6?

Answer 6

Yep, now divide 3 to both sides.

Answer 7

y=3?

Answer 8

Yes, so we have the y-value of the solution, now we can plug this into any of the two equations to find the x-value.

x = 2y - 1

x = 2(3) - 1

Solve for 'x'.

Answer 9

x=5

Answer 10

Yes, so our full solution is:

(5, 3)

Answer 11

x=2y-1 then x=2(2x-4)-1 then x=4x-8-1
x=4x-9 then x-4x=-9 then -3x=-9 then x=3 then solve for y

Answer 12

Welcome to Open Study!

You can give medals by clicking 'Best Resposne'. @priea

Answer 13

thanks but I put that in and it said it was wrong. can u help me with another one please

Answer 14

Sure, close this one and open a new one.

Answer 15

Oh, you divided wrong.. 6 / 3 isn't 3..it's 2. So the 'y' would actually be '2'. Then we plug that in and get '3' for 'x'.

So our answer would be (3, 2)..