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# could someone check these simultaneous equation answers? watch

1. the equations were

x+2y=13
x^2+y^2=9

I got the answers y=40/3 x=-43/3 And y=4 x=5

whenever I plug these in they're wrong though whats the answer
2. (Original post by jonjoshelvey21)
the equations were

x+2y=13
x^2+y^2=9

I got the answers y=40/3 x=-43/3 And y=4 x=5

whenever I plug these in they're wrong though whats the answer
Well that means you've went wrong somewhere in your working. Try again by substituting into
3. (Original post by jonjoshelvey21)
the equations were

x+2y=13
x^2+y^2=9

I got the answers y=40/3 x=-43/3 And y=4 x=5

whenever I plug these in they're wrong though whats the answer
First you rearange equation 1 by subtracting from both sides to get the equation

Then you substitute this value into equation 2 to get which you the expand to

This is simplified to

From my experiance I can see from this equation that in can't be factorised unless you use imaganary numbers which is too high a level for this. Are you sure you typed the eqautions in properly?
4. (Original post by PandahatDude)
First you rearange equation 1 by subtracting from both sides to get the equation

Then you substitute this value into equation 2 to get which you the expand to

This is simplified to

From my experiance I can see from this equation that in can't be factorised unless you use imaganary numbers which is too high a level for this. Are you sure you typed the eqautions in properly?
yeah sorry should be for the seconds equation x squared minus y squared equals nine
5. (Original post by jonjoshelvey21)
yeah sorry should be for the seconds equation x squared minus y squared equals nine
Okay, so you would instead end up with

This can then be put into the quadratic formula to find or

You then substitute these values into the equation to find that when and when

I hope this helped
6. (Original post by PandahatDude)
Okay, so you would instead end up with

This can then be put into the quadratic formula to find or

You then substitute these values into the equation to find that when and when

I hope this helped
thanks it did a lot. btw what are imaginary numbers ?
7. (Original post by jonjoshelvey21)
thanks it did a lot. btw what are imaginary numbers ?
If you ever take further maths in A Level then you get what is known as imaginary numbers. It is used when you are trying to square root a negative number which is impossible as any number times by itself is alway positive (e.g.) and therefore this is a problem when trying to solve complex eqautions which need you to find the sqaure root of a negative.

We say that the . This then leads to lots of other crazy things where you can plot imaginary numbers alongside "real" numbers on a graph etc. I won't go into to much detail but if you want try putting the in your calculator and it will come up with a math error as the number does not exist.
8. (Original post by PandahatDude)
If you ever take further maths in A Level then you get what is known as imaginary numbers. It is used when you are trying to square root a negative number which is impossible as any number times by itself is alway positive (e.g.) and therefore this is a problem when trying to solve complex eqautions which need you to find the sqaure root of a negative.

We say that the . This then leads to lots of other crazy things where you can plot imaginary numbers alongside "real" numbers on a graph etc. I won't go into to much detail but if you want try putting the in your calculator and it will come up with a math error as the number does not exist.
oh right very interesting thank you. I will research into it a bit further
9. (Original post by jonjoshelvey21)
oh right very interesting thank you. I will research into it a bit further
Imaginary numbers are A level further maths. I don't think you need to know this yet.
10. (Original post by joyoustele)
Imaginary numbers are A level further maths. I don't think you need to know this yet.
I'm kind of wishing id also taken further maths now. it sounds really interesting lol

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