1some one tell me the ans. given was -3cos2xsin4x. HOW?
6 Answers
39\frac {dy}{dx} = 3 cos^{2}(2x). (-sin(2x)) .2 = -6cos^{2}(2x)sin(2x)
1y=cos3 (2x)
dy/dx=3cos2(2x).2sin(2x).2
= -3cos(2x).cos(2X).2sin(2x)
= -3cos(2x)[2sin(2x).cos(2x)]
= -3cos(2x)sin(4x)
thus ans given z absolutely correct.................
49y=cos^{3}(2x)
\Rightarrow \frac{dy}{dx}=\frac{d}{dx}cos^{3}(2x)
\Rightarrow \frac{dy}{dx}=3cos^{2}(2x)[-2sin(2x)]=-3cos(2x)[2sin(2x)cos(2x)]=-3cos(2x)sin(4x)
any way both the answers are correct!!