`(a)/(x^4)-(b)/(x^2)+cosx`

Explanation

माना `y=(a)/(x^4)-(b)/(x^2)+cosx`
`=a.x^(-4)-b.x^(-2)+cosx`
`rArr (dy)/(dx)=(d)/(dx)(ax^(-4)-bx^(-2)+cosx)`
`=a(d)/(dx)x^(-4)-b(d)/(dx)x^(-2)+(d)/(dx)cosx`
`=a(-4)x^(-5)-b(-2)x^(-3)+(-sinx)`
`=(-(4a)/(x^5)+(2b)/(x^3)-sinx)`