cac bac nay ranh wa di bai cung mang ra ban nua
lay nhan tu chung la Cos2x thi ta co:
Cos2x.($cos^{2}3x$ - 1)=0
$\bigcup_{Cos2x= 0}^{cos^{2}3x =1}$
\Rightarrow
x= $\frac{\pi}{2} + K.\pi$
x= $\frac{K.2\pi}{3}$
x= $\frac{\pi}{3} + \frac{K.2\pi}{3}$
cong viec de dang @@
cac bac nay ranh wa di bai cung mang ra ban nua
lay nhan tu chung la Cos2x thi ta co:
Cos2x.($cos^{2}3x$ - 1)=0
$\bigcup_{Cos2x= 0}^{cos^{2}3x =1}$
\Rightarrow
x= $\frac{\pi}{2} + K.\pi$
x= $\frac{K.2\pi}{3}$
x= $\frac{\pi}{3} + \frac{K.2\pi}{3}$
cong viec de dang @@