Solving Using Substitution

Hey Everyone! I'm going to have a few emergency help questions today and early tomorrow. I have a huge test.(Doh)

My problem right now is solving with substitution, and I am given the following problem to do so with:

4x+y=5

2x-3y=13

I'm thinking I should bring up the 2x or the 3 from the bottom equation to the top? T

Thanks!

Re: Solving Using Substitution

Rearranging the first to isolate :

Now attempt to substitute this into the second equation. If you can't, then please show your working.

Re: Solving Using Substitution

Multiply the second equation through by 2 then subtract the result from the first equation.

Re: Solving Using Substitution

Re: Solving Using Substitution

Quote:

Originally Posted by

**annon25** Hey Everyone! I'm going to have a few emergency help questions today and early tomorrow. I have a huge test.(Doh)

My problem right now is solving with substitution, and I am given the following problem to do so with:

4x+y=5

2x-3y=13

I'm thinking I should bring up the 2x or the 3 from the bottom equation to the top? T

Thanks!

Since the questions states substitution I would not use pickslide's methods (which is elimination). What it wants you to do is sub an expression for either x or y into the other equation solving for one of the variables then finding the other.

In your case it is easier to subtract 4x from both sides to get . You can now sub 5-4x for y in the second equation: .

You can now find x and then use the first equation to find y

Re: Solving Using Substitution

Okay,

This is what I ended up with:

2x-4x-3y

If I plug in 2 as x and-3 as y, I am getting the answer "5..."

Re: Solving Using Substitution

Quote:

Originally Posted by

**annon25** Okay,

This is what I ended up with:

2x-4x-3y

If I plug in 2 as x and-3 as y, I am getting the answer "5..."

Soroban has answered your question.