1.

If y = sin x then \(\rm \frac{d^2y}{dx^2}\) is 1. y22. y3. 1 + y4. -y

Answer» Correct Answer - Option 4 : -y

Concept:

Suppose that we have two functions f(x) and g(x) and they are both differentiable.

  • Chain Rule: \(\frac{{\rm{d}}}{{{\rm{dx}}}}\left[ {{\rm{f}}\left( {{\rm{g}}\left( {\rm{x}} \right)} \right)} \right] = {\rm{\;f'}}\left( {{\rm{g}}\left( {\rm{x}} \right)} \right){\rm{g'}}\left( {\rm{x}} \right)\)
  • Product Rule: \(\frac{{\rm{d}}}{{{\rm{dx}}}}\left[ {{\rm{f}}\left( {\rm{x}} \right){\rm{\;g}}\left( {\rm{x}} \right)} \right] = {\rm{\;f'}}\left( {\rm{x}} \right){\rm{\;g}}\left( {\rm{x}} \right) + {\rm{f}}\left( {\rm{x}} \right){\rm{\;g'}}\left( {\rm{x}} \right)\)


Formulas:

\(\rm\frac{d\sin x}{dx} = \cos x\)

\(\rm\frac{d\cos x}{dx} =- \sin x\)

Calculation:

We have to find the value of \(\rm \frac{d^2y}{dx^2}\)

Given: y = sin x

\(\rm \frac{d^2y}{dx^2} =\rm \frac{d^2\sin x}{dx^2} = \frac{d}{dx} \left(\frac{d\sin x}{dx} \right )\)

\(= \rm\frac{d(\cos x)}{dx} =- \sin x\)

∴ \(\rm \frac{d^2y}{dx^2} = -y\)



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