I'm wondering if someone could show me how to check this, here's my work:
Use a first order differential equation to solve:
dy/dx = 2x/(1/y)
(1/y)(dy/dx) = 2x
integrate with respect to x:
∫ (1/y)(dy/dx) dx = ∫ 2x dx
ln y = x^2 + c
How would I go about checking this answer for accuracy?
Use a first order differential equation to solve:
dy/dx = 2x/(1/y)
(1/y)(dy/dx) = 2x
integrate with respect to x:
∫ (1/y)(dy/dx) dx = ∫ 2x dx
ln y = x^2 + c
How would I go about checking this answer for accuracy?
-
Ok, that's correct.
You could also solve for y as a function of x:
y = e^(x^2 + c)
y = e^(x^2) * e^c
Now since c is an arbitrary constant, then so is e^c.
We can then replace e^c with C, another arbitrary constant.
y = C e^(x^2)
====================
Check:
dy/dx = C * 2x * e^(x^2) = 2Cx e^(x^2)
2x/(1/y) = 2xy = 2x C e^(x^2) = 2Cx e^(x^2)
dy/dx = 2x/(1/y)
--------------------
Now if you wish to leave as
ln y = x^2 + c
we can check in similar fashion.
We use implicit differentiation to find dy/dx
1/y dy/dx = 2x
dy/dx = 2x/(1/y)
You could also solve for y as a function of x:
y = e^(x^2 + c)
y = e^(x^2) * e^c
Now since c is an arbitrary constant, then so is e^c.
We can then replace e^c with C, another arbitrary constant.
y = C e^(x^2)
====================
Check:
dy/dx = C * 2x * e^(x^2) = 2Cx e^(x^2)
2x/(1/y) = 2xy = 2x C e^(x^2) = 2Cx e^(x^2)
dy/dx = 2x/(1/y)
--------------------
Now if you wish to leave as
ln y = x^2 + c
we can check in similar fashion.
We use implicit differentiation to find dy/dx
1/y dy/dx = 2x
dy/dx = 2x/(1/y)