What is the derivative of y with respect to x at the point (2,-3)?

In summary, in order to find dy/dx at the point (2,-3) when y^2 - 2xy=21, you need to differentiate the function implicitly. The correct solution is to isolate dy/dx on one side and solve for it by dividing both sides by the coefficient of dy/dx.
  • #1
drandhawa
9
0

Homework Statement


If y^2 - 2xy=21, then dy/dx at the point (2,-3) is ?


Homework Equations


y^2 - 2xy=21


The Attempt at a Solution


I know that I have to differentiate the function. I just do not know how to do it: implicitly or explicitly.
 
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  • #2
Why not try both ways?

Actually, you should get the same (correct) answer doing either.)
 
  • #3
i tried to diff it in terms of dy/dx but I don't think i got it right. i got dy/dx to equal 2y+2x
 
  • #4
what I did was...
y^2= 2xy +21
2dy/dx=2(y+x(dy/dx))
2(dy/dx)= 2y+2x(dy/dx)
Divide by dy/dx on both sides
dy/dx=2y+2x
 
  • #5
Never mind, I see what I did wrong. I should have put the two dy/dx's on the same side, take out dy/dx and then just divide to get dy/dx alone.
 
  • #6
y^2= 2xy +21
2dy/dx=2(y+x(dy/dx))


This step is wrong. It should be
2y*dy/dx = 2(y+x(dy/dx))
 

FAQ: What is the derivative of y with respect to x at the point (2,-3)?

What is differentiation?

Differentiation is a mathematical process used to find the rate of change of a function with respect to its independent variable. It is used to calculate the slope of a curve at a specific point, or the instantaneous rate of change of a quantity.

What is dy/dx in differentiation?

dy/dx is a notation used to represent the derivative of a function. It is read as "the derivative of y with respect to x" and is used to describe the rate of change of y with respect to x at a specific point.

What is the differentiation dy/dx problem?

The differentiation dy/dx problem refers to finding the derivative of a function at a specific point using the limit definition of a derivative. This involves finding the slope of a curve at a point by taking the limit of the slope of a secant line as the two points get closer together.

How do you solve a differentiation dy/dx problem?

To solve a differentiation dy/dx problem, you can use the limit definition of a derivative or apply differentiation rules such as the power rule, product rule, and chain rule. You can also use differentiation tables or software programs to find the derivative of a function.

What is the importance of solving differentiation dy/dx problems?

Solving differentiation dy/dx problems is important in many fields such as physics, engineering, economics, and finance. It allows us to calculate the rate of change of a quantity, which is crucial in understanding the behavior of a system or predicting future values. It also helps in optimization problems where we need to find the maximum or minimum of a function.

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