math
posted by anon .
cos2xsinx=0. Factor and solve for sinx

1  2sin^2 x  sinx = 0
2sin^2 x + sinx  1 = 0
(2sinx  1)(sinx + 1) = 0
sinx = 1/2 or sinx = 1
in degrees, x = 30° , 150° , 270°
in radians, x = π/5 , 5π/6 , 3π/2 
Thanks. I was wondering, why is it "+ sin x" in the second step?

do you just change all the signs of the terms? if so, why is this necessary?

I multiplied each term by 1
(notice all the signs have switched)
I like my quadratics to start with a positive coefficient, although that would not be necessary.
It just makes it easier to factor. 
ok thank you.