Q. A curve C has equationy=x(sinx)x>0y>0(a) Find, by firstly taking natural logarithms, an expression for (dy)/(dx) in terms of x and y.
Apply Logarithm Property: To find the derivative of y with respect to x, we will first take the natural logarithm of both sides of the equation y=x(sinx) to make use of the properties of logarithms.We apply the logarithm to both sides:ln(y)=ln(x(sinx))Using the property of logarithms that allows us to bring the exponent down in front of the log, we get:ln(y)=sin(x)⋅ln(x)
Differentiate with Chain and Product Rule: Now we differentiate both sides of the equation with respect to x. The left side will use the chain rule, and the right side will use the product rule.Differentiating the left side:dxd[ln(y)]=y1⋅dxdyDifferentiating the right side:\frac{d}{dx} [\sin(x) \cdot \ln(x)] = \cos(x) \cdot \ln(x) + \sin(x) \cdot \left(\frac{\(1\)}{x}\right)
Solve for \(\frac{dy}{dx}: Now we equate the derivatives from both sides to solve for dxdy.y1⋅dxdy=cos(x)⋅ln(x)+sin(x)⋅(x1)To isolate dxdy, we multiply both sides by y:dxdy=y⋅(cos(x)⋅ln(x)+sin(x)⋅(x1))
Substitute back into Expression: We know from the original equation that y=x(sinx), so we can substitute this back into our expression for dxdy.dxdy=x(sinx)⋅(cos(x)⋅ln(x)+sin(x)⋅(x1))This is the expression for the derivative of y with respect to x in terms of x and y.