How to work with simultaneous equations - eliminating x

This video is all about how to work with simultaneous equations and forms part of the playlists on simultaneous linear equations and GCSE Higher revision.

The question is around level 7 - 9 and asks to solve x^2 + y^2 = 13 by substituting x - 2y = 1. The idea is to rearrange to eliminate x by rearranging so that x = 1 + 2y and use that value in xsquared + ysquared = 13.


I hope the video helps and please do leave a comment - thanks!

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[ShadowX-lgbt]

Hi. I really like your videos but when I use the quadratic equation. Sometimes it says Math error does it mean I can use sum and product method? And when I retry the question with sum and product method it can work. Obviously not for this question. It was a question previously I saw.

[minermon]

Would you mind doing something on direct proportions

[chrisw]

first time attempting this wheres the x gone and how did 2+1 get squared in brackets

[asdfqwerty]

Hey that exact question is on my maths homework lol

[sudeepdhakal]

Hi I am doing this topic in maths and I am good at it and by the way I m been teach is very different then ur way

[lemonysabi]

What if both equations are to the second power in the x and y?

[bantercomedy]

sir I made y= 3.4 y=-1.5 x=1.2 and x=-2?

[sudeepdhakal]

example.
x -2= 2
x+2=2
=(add them all) 2x =4
x=2

[sudeepdhakal]

- + cancle each other so all that is left is the answer

[qai]

he skipped too many steps i lost track