Mathematics
22 Online
OpenStudy (anonymous):
Solve: sin^(2) x - Sin x =0, for 0≤x≤3
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OpenStudy (michele_laino):
here we have to change variable, namely:
\[\Large \sin x = t\]
OpenStudy (michele_laino):
after that your equation can be rewritten as follows:
\[\Large {t^2} - t = 0\]
OpenStudy (michele_laino):
please solve that equation for t
OpenStudy (anonymous):
So t=0?
OpenStudy (michele_laino):
hint, we can factor out t at left side, so we can write:
\[\Large t\left( {t - 1} \right) = 0\]
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OpenStudy (anonymous):
Oh, so t= 0 and 1?
OpenStudy (michele_laino):
that's right!
OpenStudy (michele_laino):
now
t=0 means:
sin x=0
what is x?
OpenStudy (anonymous):
x= Radical 3 over 2?
OpenStudy (anonymous):
Oops!
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OpenStudy (michele_laino):
no, the solution of that equation:
sin x=0, are:
\[x = 0,\pi ,2\pi ,3\pi ...\]
OpenStudy (michele_laino):
nevertheless only x=0, is acceptable, since pi >3
OpenStudy (anonymous):
Oh, i get it! Thank you!
OpenStudy (michele_laino):
please wait, we have to solve this equation:
t=1
which means
sin x =1
OpenStudy (michele_laino):
for which values x, we have:
sin x= 1?
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OpenStudy (michele_laino):
\[\sin x = 1 \Rightarrow x = ...?\]
OpenStudy (anonymous):
Pie over 2
and
3 pie over 2
OpenStudy (michele_laino):
no, the solutions are:
\[x = \frac{\pi }{2},2\pi + \frac{\pi }{2},4\pi + \frac{\pi }{2}...\]
OpenStudy (anonymous):
Oh yea, my bad.
OpenStudy (michele_laino):
nevertheless only x= pi/2 is acceptable
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OpenStudy (anonymous):
I get it. thanks :D
OpenStudy (michele_laino):
thanks! :)