Q. We are given that dxdy=xsin(y).Find an expression for dx2d2y in terms of x and y.dx2d2y=
Differentiate First Derivative: To find the second derivative of y with respect to x, we need to differentiate the first derivative with respect to x. The first derivative is given by dxdy=xsin(y). We will use the quotient rule and the chain rule to differentiate this expression.
Apply Quotient Rule: The quotient rule states that for a function h(x)=g(x)f(x), the derivative h′(x) is given by h′(x)=(g(x))2g(x)f′(x)−f(x)g′(x). In our case, f(x)=sin(y) and g(x)=x. We also need to remember that when we differentiate f(x) with respect to x, we need to use the chain rule because y is a function of x.
Differentiate sin(y): First, we differentiate f(x)=sin(y) with respect to x. Using the chain rule, we get f′(x)=cos(y)⋅dxdy. We already know that dxdy=xsin(y), so we can substitute this in to get f′(x)=cos(y)⋅xsin(y).
Differentiate x: Next, we differentiate g(x)=x with respect to x. The derivative of x with respect to x is 1, so g′(x)=1.
Apply Quotient Rule: Now we apply the quotient rule. We have h′(x)=x2x⋅cos(y)⋅(sin(y))/x−sin(y)⋅1. This simplifies to h′(x)=x2cos(y)⋅sin(y)−sin(y).
Factor out sin(y): We can factor out sin(y) from the numerator to get h′(x)=sin(y)⋅(cos(y)−1)/(x2).
Final Second Derivative: This expression, h′(x), is the second derivative of y with respect to x, which we denote as dx2d2y. Therefore, dx2d2y=sin(y)⋅x2cos(y)−1.
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