Assuming the correct tools of differentiation have been taught, we can tackle each term seperately and then rearrange to have dy/dx as the subject.
Taking a look at the first term, x^2, differentiating this term would become 2x (diffentiating x^n = nx^n-1)
Taking a look at the second term, 2y^2, it would appear we could differentiate it just like we did the first term. However this variable involves y and not x, meaning we must differentiate it implicitly.Therefore differentiating 2y^2 would become 4y(dy/dx)
Taking a look at the third term, 2xy, we immediately notice that it has both x terms and y terms involved; this should immediately hint to us that the product rule should be used. Therefore differentiating 2xy would become 2y + 2x(dy/dx) (Differentiating any term involving any other variable other than x with respect to x would require implicit differentiation).
Differentiating any constant (2) would = 0
Putting all these terms together would give:
2x + 4y(dy/dx) + 2y + 2x(dy/dx) = 0
With our basic GCSE knowledge of subject formula we can get:
2x + (dy/dx)(4y+2x) = 0
dy/dx = (-2x) / (4y+2x)