A few days ago

help solve a maths differentiation qn please!?

y= [ x^2 ] [(cos 3x )^2]

can someone help to differentiate this for me?

I tried but my ans looks weird.

Top 2 Answers
A few days ago
Franck Z

Favorite Answer

([x^2][(cos 3x)^2])’

= [x^2]'(cos 3x)^2 + (x^2)[(cos 3x)^2]’

= 2x (cos 3x)^2 + (x^2) * 2 * (cos 3x)’ cos(3x)

= 2x (cos 3x)^2 – 2 x^2 (3x)’ sin(3x) cos(3x)

= 2x (cos 3x)^2 – 6 x^2 sin(3x) cos(3x)


A few days ago
dy/dx = 2x * (cos(3x))^2 – [2x^2] * [sin(3x)]

i think of these problems like this:

break into 2 parts like this: x^2 and [(cos 3x )^2]

then i say: front times the derivative of the back to get: -[2x^2] * [sin(3x)]

plus back times the derivative of the front: 2x * (cos(3x))^2