A few days ago
mercin5

Suppose e^(xy) = x – 2y -1 defines y implicitly as a function of x. What is the slope of the the tangent line?

The end of the second sentence on the question got cut off. Here it is: What is the slope of the tangent line to the curve at the point (2,0)

Top 2 Answers
A few days ago
Anonymous

Favorite Answer

Obviously, you’re going to take the derivative implicitly. This is easy with the right side of the equation. The left side will require, first, the Chain Rule and then the Product Rule.

d/dx (e^(xy)) = e^(xy) * d/dx(xy) (Chain Rule)

= e^(xy) (x dy/dx + y dx/dx) (Product Rule)

dx/dx is clearly 1, so you end up with

d/dx(e^(xy)) = (x dy/dx + y) e^(xy)

On the right, you get

d/dx (x – 2y – 1) = 1 – 2 dy/dx

So, after implicit differentiation, you get

(x dy/dx + y) e^(xy) = 1 – 2 dy/dx

Solve algebraically for dy/dx, plug in your values for x and y, and you’re done.

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A few days ago
Jonathan D
I’m having difficulty understanding what e is equal to? Because x-2y-1 is a line… and the slope of the tangent line of a line is the same as the slope of the line. And when you say e are you talking about the base of natural log. The definition of the tangent line is a line which intersects only one specific point on that function… when dealing with a line the tangent line is that same line… but to find the slope of the tangent line for non linear function at a specific point… you take the derivative of that function and sub in the point for the x and the y… and it should give you a specific value, and that value is the slope on that function at that specific point… i don’t know if that helped at all…
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