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

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- February 4th 2013, 03:57 PMiceman202290Verify 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 - February 4th 2013, 04:36 PMtopsquarkRe: Verify the set of solutions of the de on the interval
- February 4th 2013, 04:51 PMiceman202290Re: 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))