The least value of the expression `y=(1)/((3sin^(2)x + 3 sin x cos x + 7 cos ^(2)x))` is equal to

Options

A. `(2)/(15)`
B. `(2)/(5)`
C. `(2)/(3)`
D. `-(2)/(5)`

Explanation

`I_(n) = inte^(-x)s^(n)`
`I_(n) = intn.(s)^(n-1).c.e^(-x)dx`
`I_(n) = n(s)^(n-1).c.e^(-x)(-1)]_(0)^(oo)+int(n(n-1)s^(n-2).c^(2)-ns^(n))e^(-x)dx`
`I_(n) = int(n(n-1).S^(n-2)-n(n-1)s^(n)-n.s^(n))e^(-x)dx`
`I_(n) =n(n-1).I_(n-2)-n^(2).I_(n)`
`I_(n) =(n(n-1))/(1+n^(2)).I_(n-2)`