Implicit differentiation dy/dx=xy^2

In summary, the conversation discusses solving a differential equation using implicit differentiation and integration. The solution is found to be y=-2/x^2 + 3, leading to the answer of (B) -2/(x^2 - 3). The conversation also mentions the importance of being aware of linear and non-linear functions when using implicit differentiation.
  • #1
mandymanny
10
0

Homework Statement


If dy/dx=xy^2 and x=1 when y=1, then y=

(A) x^2
(B) -2/(x^2 -3)
(C) x^2 + 3
(D) 2/(x^2 +1)
(E) (x^2 -3)/2


Homework Equations





The Attempt at a Solution



dy/dx=xy^2
dy=xy^2dx
dy/y^2=x dx
∫dy/y^2=∫x dx
-1/y = x^2/2 + C
y=-2/x^2 + C
1=-2/1^2 + C
C=3
y=-2/x^2 +3

but that's not the answer...

please help i have the AP test tomorrow.
thanks
much appreciated
 
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  • #2
Watch the step between line 5 and 6. f(x) = x^-1 is not linear.
 
  • #3
That's not really implicit differentiation -- it's a diff. eq.
 
  • #4
yes?

when i integrate, it's y^-1/-1 right? not just y^-1
??
 
  • #5
Nevermind I got it.
Answer is B :)
 

1. What is implicit differentiation?

Implicit differentiation is a method used to find the derivative of an equation that is not explicitly expressed in terms of the independent variable. This means that the equation may have both the dependent and independent variables on both sides of the equation.

2. How do you solve for dy/dx in implicit differentiation?

To solve for dy/dx in implicit differentiation, you need to follow the steps of the chain rule. First, you will differentiate each term in the equation with respect to the independent variable. Then, you will solve for dy/dx by isolating it on one side of the equation.

3. Why is xy^2 used in implicit differentiation?

The equation xy^2 is commonly used in implicit differentiation because it represents a non-linear relationship between x and y. This allows for a more complex and challenging differentiation problem, which can help to strengthen understanding of the concept.

4. What is the purpose of finding dy/dx using implicit differentiation?

The purpose of finding dy/dx using implicit differentiation is to understand the rate of change of a variable that is not explicitly expressed in the equation. This is important in many scientific fields, such as physics and engineering, where understanding the rate of change is crucial in solving problems and making predictions.

5. Can implicit differentiation be used for any type of equation?

Yes, implicit differentiation can be used for any type of equation as long as it contains both the dependent and independent variables on both sides of the equation. However, the complexity of the problem may vary depending on the type of equation.

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