# Solve for all values of x

• Apr 7th 2009, 10:52 PM
Jd09
Solve for all values of x
sin^2(x)=sinx

How would I go about answering this?
Would it work if I substitute x?
• Apr 7th 2009, 10:54 PM
Jhevon
Quote:

Originally Posted by Jd09
sin^2(x)=sinx

How would I go about answering this?
Would it work if I substitute x?

this is a quadratic in $\displaystyle \sin x$. to see this, let $\displaystyle a = \sin x$, then you have

$\displaystyle a^2 = a$

$\displaystyle \Rightarrow a^2 - a = 0$

now what?
• Apr 7th 2009, 11:00 PM
Jd09
I had done the same, using the 'm' as a variable but I am not sure where to go on to next.
• Apr 7th 2009, 11:04 PM
Jhevon
Quote:

Originally Posted by Jd09
I had done the same, using the 'm' as a variable but I am not sure where to go on to next.

you should review algebra. at the very least, if you don't know what to do, apply the quadratic formula. in this case, it is overkill though

$\displaystyle m^2 - m = 0$

$\displaystyle \Rightarrow m(m - 1) = 0$

$\displaystyle \Rightarrow m = 0 \text{ or } m - 1 = 0$