Find d^2y/dx^2 at point P(2,1) if y is a differentiable function of x satisfying the equation:
x^3+2y^3=5xy
x^3+2y^3 = 5xy
3x^2 + 6y^2 y' = 5y + 5xy'
y'(6y^2-5x) = 5y-3x^2
y' = (5y-3x^2)/(6y^2-5x)
y" = [(5y'-6x)(6y^2-5x)-(5y-3x^2)(12yy'-5)]/(6y^2-5x)^2
2xy(54x^3-270xy+108y^3+125)
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(5x-6y^2)^3
= 125/16