reggiwilliams
Junior Member
- Joined
- Mar 6, 2024
- Messages
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Can you tell me how to solve the simultaneous equations
X^-xy+3y^=15
X^+xy-y^=5
X^-xy+3y^=15
X^+xy-y^=5
Can you tell me how to solve the simultaneous equations
X^-xy+3y^=15
X^+xy-y^=5
Possibly you are using "^" as if it were the exponent 2 (which is very nonstandard). And quite likely you didn't mean X to be different from x.Can you tell me how to solve the simultaneous equations
X^-xy+3y^=15
X^+xy-y^=5
I added the equations together, as I suggested, and solved the resulting equation for y in terms of x, then plugged that into the second equation. That results in a quartic equation, but one that is really a quadratic in x^2, and is easily solved.Stumbled across question when revising for exam in June. Have been doing a correspondence course.
Can’t find in any textbook the method to solve. Only way I can see is by trial or error which can’t be right.
Even when you isolate y still get a long fourth degree polynomial equation which I can’t factorise
If you really squared both sides here, you would still have a radical:Here are my workings which show y= -or + sqr of 5 and similarly x = - or + sqr of 5
Is that correct
From trial or error also discovered x=-3 y=1 and when x=3 y =-1 but have no idea the method to get to this answer
See where I went wrong. squaring both sides properly left with equation 5y^4 -30y^ + 25 which when factorised gives me (5y^-5)(y^-5)