What Value of k Makes x(t)=k a Solution to the Differential Equation?

the7joker7
Messages
111
Reaction score
0

Homework Statement



Find the value of k for which the constant function x(t)=k is a solution of the differential equation 9t_{2}\frac{dx}{dt} -3x + 7 = 0.

The answer: k -2.33

Homework Equations



-

The Attempt at a Solution



I'm a little confused on where to start...I was under the impression I had to factor and find what values would set the function equal to zero, so I did that, but it didn't come out right. Help?
 
Physics news on Phys.org
Since x(t)=k doesn't have a term including t, we have dx/dt=0.The rest is just simple arithmetic!
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
Back
Top