Doubt in DSE -2009 paper(option A)

Posted by Niharika Mishra on Dec 21, 2010; 11:19am
URL: http://discussion-forum.276.s1.nabble.com/Doubt-in-DSE-2009-paper-option-A-tp5855405.html

Hi

 I am a DSE aspirant and solving 2009 dse option A paper .provided in site.


I have doubt in 3rd,4th and 5th question

3rd question- I think question is wrong because i tried doing it by substitution but exponent has x^2 but we dont have xdx.Please let me know if there is some other way of solving this problem.

3. 1.96∫x2 / 2 dx
¥e
-is approximately
a) 0.025
b) 2p
c) 0.025/ p
d) 0.025 2p

4. Consider maximizing f (x, y) = x2 - y2 subject to the constraint x + y = 1, where x
and y are real numbers. This problem has
a) no solution.
b) a unique solution.
c) 2 solutions.
d) an infinity of solutions.


For this question I found  out partial derivatives.
I took f(x)=x^2-y^2
and g(x)=x+y-1

taking out partial derivatives
^g(x)=(1,1)
^f(x)=(2x,2y)

(2x,2y)=lamb(1,1)

x=lamb/2
y=lamb/2
x+y=1
lamb/2+lamb/2=1
lamb=1
x=1/2
y=1/2

so I am getting unique solution for them x=1/2 and y=1/2
but in answers its given as no solution



5th question I have no clue how u got the solution