`a_n=nsin(1/n)`
Apply n'th term test for divergence, which states that,
If `lim_(n->oo) a_n!=0` , then `sum_(n=1)^ooa_n` diverges
`lim_(n->oo)nsin(1/n)=lim_(n->oo)sin(1/n)/(1/n)`
Apply L'Hospital's rule,
Test L'Hospital condition:`0/0`
`=lim_(n->oo)(d/(dn)sin(1/n))/(d/(dn)1/n)`
`=lim_(n->oo)(cos(1/n)(-n^(-2)))/(-n^(-2))`
`=lim_(n->oo)cos(1/n)`
`lim_(n->oo)1/n=0`
`lim_(u->0)cos(u)=1`
By the limit chain rule,
``
`=1!=0`
So, by the divergence test criteria series diverges.
` `
`a_n=nsin(1/n)`
Apply n'th term test for divergence, which states that,
If `lim_(n->oo) a_n!=0` , then `sum_(n=1)^ooa_n` diverges
`lim_(n->oo)nsin(1/n)=lim_(n->oo)sin(1/n)/(1/n)`
Apply L'Hospital's rule,
Test L'Hospital condition:`0/0`
`=lim_(n->oo)(d/(dn)sin(1/n))/(d/(dn)1/n)`
`=lim_(n->oo)(cos(1/n)(-n^(-2)))/(-n^(-2))`
`=lim_(n->oo)cos(1/n)`
`lim_(n->oo)1/n=0`
`lim_(u->0)cos(u)=1`
By the limit chain rule,
``
`=1!=0`
So, by the divergence test criteria series diverges.
` `
No comments:
Post a Comment