Write an anti-derivative for each of the following function using method of inspection :
`(i) cos3x` `(ii) 3x^(2)+5x^(4)`

Explanation

We look for a function whose derivative is `cos3x`. Recall that
`(d)/(dx)(sin3x)=3cos3x`
or `cos3x=(1)/(3)(d)/(dx)(sin3x)=(d)/(dx){(1)/(3)sin3x}`
`:.` an anti-derivative of `cos3x` is `(1)/(3)sin3x`.
`(ii)` We look for a function whose derivative is `3x^(2)+5x^(4)`. Note that,
`(d)/(dx){x^(3)+x^(5)}=3x^(2)+5x^(4)`
`:.` An anti-derivative of `3x^(2)+5x^(4)` is `{x^(3)+x^(5)}`.