A curve has the equation 2x2+xy+2y2=202x^2 + xy + 2y^2 = 202x2+xy+2y2=20
The gradient of the tangent to the curve is -1 at the points R R\,R and SSS.
Show that x−y=0x - y = 0x−y=0 at R R\,R and SSS.
Find the coordinates of R R\,R and SSS.
Practise Edexcel A Level Maths 9.8 Implicit Differentiation with exam-style questions for A Level Maths. 48 questions, matched to the Edexcel A Level Maths (9MA0) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.
