Hello everyone, when i'm doing these problems i always make sure i put a negative inside the sin(x) function, then just later take it out like(adsbygoogle = window.adsbygoogle || []).push({});

cos(2t)+sin(-2t) = cos(2t)-sin(2t); Because sin is an odd function.

But my professor says f it and never does, for instance here is my work, i came out with the professors answer but he didn't use the negative at all, he just acted as if it was r1 = -9+2i, r2 = -9+2i, rather than r1,2 = -9+/- 2i;

http://suprfile.com/src/1/2dq85j/lastscan.jpg [Broken]

He does this with all his problems, even in an e-mail, he told me, don't worry about putting the negative sign inside the sin function. So is this true?

THe professors answer was:

y = e^(-9t)(18sin(2t)+3cos(2t))

which is the same as mine once i take that negative sign out of the sin(x)

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# Homework Help: Does this negative sign even matter in sin(x)?

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