MHB Solving the Initial Value Problem for x'=x^3 with x(0)=1

simo1
Messages
21
Reaction score
0
solve the initial value problem:
x'=x^3 x(1)=1

my work

dx/x^3 =dt
then I integrated wrt t and obtained
x^(-2) = t + c(c0nstant)
where then
this is 1/x^2 =t+c
1/x = square root of (t+c)
then
x= 1/sqrt(t+c)

now when i apply the Initial value problem i get c = 0 and that is incorrect. where am i going wrong
 
Physics news on Phys.org
the intergral of x^-3 is (1/2)multiply by 1/x^2=t+c
then your constant value will be 3:)
 
onie mti said:
the intergral of x^-3 is (1/2)multiply by 1/x^2=t+c
then your constant value will be 3:)

Actually it's -(1/2)(1/x^2), or -(1/2)x^{-2}
 
Thread 'Direction Fields and Isoclines'
I sketched the isoclines for $$ m=-1,0,1,2 $$. Since both $$ \frac{dy}{dx} $$ and $$ D_{y} \frac{dy}{dx} $$ are continuous on the square region R defined by $$ -4\leq x \leq 4, -4 \leq y \leq 4 $$ the existence and uniqueness theorem guarantees that if we pick a point in the interior that lies on an isocline there will be a unique differentiable function (solution) passing through that point. I understand that a solution exists but I unsure how to actually sketch it. For example, consider a...
Back
Top