The reason I posted it here was that some guy in mathlinks used an useful substtituiton of putting x as tanθ...but my query is why such a substitution - I mean what hinted at that?
Solve for positive reals (x,y,z)
z^2+2xyz=1
3x^2y^2+3y^2x=1+x^3y^4
z+zy^4+4y^3=4y+6y^2z
It's been a while no -one has really given any elaborate soln for this.....
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2 Answers
					
			Devil
					·2009-12-20 08:26:06
			
			
			
					
			Lokesh Verma
					·2009-12-21 08:05:30
			
			
		The hint of such a substitution comes from equation 2...
which is also a quadratic in y2
Think of the formula of tan 3k... specially in the second equation..

