Simultaneous Equations - Substitution

Hey,

Well I'm not very clear on this.. I know that x or y is needed to be made the subject. And then substituting the other equation in

the two equations are;

x+3y=11
4x-7y=6

So would I make X the subject (as its the easier one)

x=11 - 3y
Then how would I go about adding the second equation

You don't add the second equation if you are trying to solve by substitution. Substitute into the second equation to obtain $4(11-3y)-7y=6$ and then solve the linear equation to find y.

Oh that is what I meant.. but surely you couldn't work it out from 44-12y-7y=6?

so would it just be 5y = 60?

No!

$44-12y-7y=6$

Collect like terms:

$44-19y=6$

Subtract 6 from each side:

$38-19y=0$

Add 19y to each side:

$19y=38$

and so on.

/

How would you go about 3x-y=7 and 10x +3y = -2
think the low numbers / minus answer is confusing me a bit

How would you go about 3x-y=7 and 10x +3y = -2
think the low numbers / minus answer is confusing me a bit

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