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Let

y=arctan(x)

Solve the equation

4dydx=5d2ydx2

If you take tan of both sides first, you have

tan(y)=x

and you can use implicit differentiation to find

dydx

If your expression for dydx contains a sec2(y), remember that

1+tan2(y)=sec2(y)

and notice that

tan(y)=x

so you can give dydx in terms of x only!


Once you have an expression for dydx in terms of x only, you can find d2ydx2 without using implicit differentiation - you just need the chain (or quotient) rule.


Let the roots be α,βQ.

give the value of

104(p3+q3)