Find 
, when
and 
as 
Differentiating it with respect to 
using the product rule,
……(1)
And, 
Differentiating it with respect to 
using the product rule,
……(2)
divide equation (2)by (1)
10
Find , when
and
as
Differentiating it with respect to using the product rule,
……(1)
And,
Differentiating it with respect to using the product rule,
……(2)
divide equation (2)by (1)