Need help on this problem

http://imgur.com/0KPop.jpg

have 0 idea what to do/how to start it... (Worried)

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- Oct 7th 2010, 05:46 PMstiitchesTangent to Given Curve
Need help on this problem

http://imgur.com/0KPop.jpg

have 0 idea what to do/how to start it... (Worried) - Oct 7th 2010, 06:03 PMJhevon
- Oct 7th 2010, 06:05 PMstiitches
- Oct 8th 2010, 05:40 AMHallsofIvy
In order for a line to be tangent to a curve, at a given point, both curve and line must pass through the point and must have the same derivative there.

So you need to find c**and**x such that $\displaystyle y= \frac{5}{6}x+ \frac{15}{2}= c\sqrt{x}$ and they have the same derivative for that x. That is two equations to solve for x and c.

I will give you one derivative free- the derivative of $\displaystyle y= \frac{5}{6}x+ \frac{15}{2}$ is $\displaystyle \frac{5}{6}$, for all x. What is the derivative of $\displaystyle c\sqrt{x}$? (That**will**depend on x.)