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Activity 7.4 Supplement

1.

The curve \(x\fe{\sin}{xy}=y\) is shown in Figure 7.4.1.

Find a formula for \(\lz{y}{x}\) and use that formula to determine the \(x\)-coordinate at each of the two points the curve crosses the \(x\)-axis. (Note: The tangent line to the curve is vertical at each of these points.) Scales have deliberately been omitted in Figure 7.4.1.

Figure 7.4.1. \(x\fe{\sin}{xy}=y\)
2.

For the curve \(x\fe{\sin}{xy}=y\) plotted in Figure 7.4.1, find the slope of the tangent line at \(\point{\sqrt{\sfrac{\pi}{3}}}{\sqrt{\sfrac{\pi}{12}}}\text{.}\)

3.

Solutions to the equation \(\fe{\ln}{x^2y^2}=x+y\) are graphed in Figure 7.4.2.

Determine the equation of the tangent line to this curve at the point \(\point{1}{-1}\text{.}\)

Figure 7.4.2. \(\fe{\ln}{x^2y^2}=x+y\)
Hint

It is easier to differentiate if you first use rules of logarithms to completely expand the logarithmic expression.

Use the process of logarithmic differentiation to find a first derivative formula for each of the following functions.

4.

\(y=\dfrac{x\fe{\sin}{x}}{\sqrt{x-1}}\)

5.

\(y=\dfrac{e^{2x}}{\fe{\sin^4}{x}\sqrt[4]{x^5}}\)

6.

\(y=\dfrac{\fe{\ln}{4x^3}}{x^5\fe{\ln}{x}}\)