Thread: Solving simultaneous eqautions by inspection

Hi,

I have attached what I am trying to do hopefully it is clear any ideas?

Thanks

Subtract the 2nd equation from the first equation and you have

-2y = -2 so y = 1 then substitute y = 1 into 1st equation and you have

x + 8(1) = 4 so x = -4

Originally Posted by Caity

-2y = -2 so y = 1

Thanks for that but why does -2 become y=1, I would think logically it was y=-2

Subtract the two equations.



Divide both sides of the equation by -2.





Substitute y = 1 into the first equation and solve for x.

Thanks that really helped but I got stuck again on this one

1

2

So we ignore the 3y as is 0.

On the right:
On the left:

Therfore:


Now we substitute into formulae 1, because it has the lowest number on right











Although the answer says

Hope this is clear, and thank you.

You have it correct up to -3y = -3
then you divide both sides by the -3 because you want y by itself.
so y= 1 not -1. sometimes the answers in the book have typos

Hey thanks for that. Ive just got to the bit where the y or x's are more than 1 never knew u had to devide ... Thanks