4 Answers
Lokesh Verma
·2010-07-16 10:16:31
first is kind of straightforward...
derivative is zero at 2, f(2)=-1
and the double derivative is +ve or zero.. (if it turns to be zero.. then go for the sign test)
Lokesh Verma
·2010-07-16 10:17:18
take a tangent to xy=-1
then find the condition of repeated roots with the first curve
(hint for the second problem)
Subhomoy Bakshi
·2010-07-16 17:25:32
for no 3!
draw graph to get maxima and minima!
else consider the points(without the graph)::
1) derivative=0
2) end points!!!
bascally we have to find maxima and minima! by any method that is!
sagnik sarkar
·2010-07-17 00:39:34
For no 3, consider g(x)=x-sinx-a
Thus,g'(x)=1-cos>0
Thus g(x) is increasing.
Therefore to have a root between (-pi/2,pi/2),
g(-pi/2)*g(pi/2)<0
Hence,c is the correct answer.