# Verify the set of solutions of the de on the interval

• Feb 4th 2013, 02:57 PM
iceman202290
Verify the set of solutions of the de on the interval
Having trouble with proving it, Y''-Y'-12Y=0; e^-3x, e^4x, (-inf, inf)

so it says in the answers that cause W(e^-3x,e^4x)=e^7x obviously it can't equal 0 but how do you come up with the e^7x? I am missing something somewhere.

Thanks
• Feb 4th 2013, 03:36 PM
topsquark
Re: Verify the set of solutions of the de on the interval
Quote:

Originally Posted by iceman202290
Having trouble with proving it, Y''-Y'-12Y=0; e^-3x, e^4x, (-inf, inf)

so it says in the answers that cause W(e^-3x,e^4x)=e^7x obviously it can't equal 0 but how do you come up with the e^7x? I am missing something somewhere.

Thanks

It's probably simply asking for you to test the solutions to see if there are correct.

-Dan
• Feb 4th 2013, 03:51 PM
iceman202290
Re: Verify the set of solutions of the de on the interval
when solving using the quadratic formula and you have m'' and m' so that you get Y=C(e^(m"x))+K(e^(m'x)) where C,K are arbiturary constants does order matter? Like can it be written Y=K(e^(m'x))+C(e^(m"x))