Determining vector in a direction field

Click For Summary
SUMMARY

The discussion focuses on determining the vector in a direction field for the differential equation y' = 1 + 2ty at specific points (2, 0) and (3, -2). At (2, 0), the slope is calculated as dy/dt = 1, leading to the vector <1, 1>. At (3, -2), the slope is dy/dt = -11, resulting in the vector <1, -11>. The key takeaway is that the direction field can be established directly from the differential equation without the need for integration.

PREREQUISITES
  • Understanding of differential equations, specifically first-order linear equations.
  • Familiarity with direction fields and their graphical representation.
  • Knowledge of slope calculations in the context of vector fields.
  • Basic integration concepts, though not directly required for this problem.
NEXT STEPS
  • Study the concept of direction fields in differential equations.
  • Learn how to derive slopes from differential equations without integration.
  • Explore examples of first-order linear differential equations and their solutions.
  • Investigate graphical methods for visualizing direction fields and vector fields.
USEFUL FOR

Students studying differential equations, educators teaching mathematical concepts related to vector fields, and anyone interested in understanding direction fields in the context of calculus.

kpou
Messages
24
Reaction score
0

Homework Statement



Determine the vector in the direction field( in the form of < 1, ? >) correspond-
ing to the given point.
y' = 1 + 2ty at (2, 0), at (3, -2).

Homework Equations


The Attempt at a Solution



y'-2ty=1
p(t)=-2t ; u(t)=e^(-t^2)
e^(-t^2)-2te^(-t^2)=e^(-t^2)
e^(-t^2)=integral(e^(-t^2)dt)+c

I am confused where to go from here. I think I am supposed to set up the integral definitely. When i do from 0->0 I get c=2.
From here I am not sure where to go. Do I set up the integral from 0->1 (since I am trying to find a vector with t =1)? When I do this it comes out to <1, 2.63> What made me doubt this was how I am supposed to set up the problem at point (3,-2).

Do I plug in t=0 and for the integral do 0->1 ?

And plug in t=3 and do 3->4 integral ?

This does not really seem right though -.-

My weakness may lie in the fact that I have no notes on how to find a vector <1, ?>.
 
Last edited:
Physics news on Phys.org
you are asked to find the direction field. That means that you do NOT want to solve the equation and do NOT want to integrate. All the information you need is in the differential equation.

At (2, 0) (which I am going to interpret as t= 2, y= 0) dy/dt= 1+ 2(2)(0)= 1 so your vector must have slope 1: the two components must be equal, if the vector is <x, y>, then y/x= 1.

At (3, -2), dy/dt= 1+ 2(3)(-2)= -11. The slope must be -11: if the vector is <x, y>, then y/x= -11.

In fact, this whole problem is pretty close to being trivial!
 

Similar threads

Replies
6
Views
3K
Replies
12
Views
2K
Replies
2
Views
2K
Replies
2
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 24 ·
Replies
24
Views
4K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K