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Vectors

Blazing goIITian

Joined:	29 Mar 2008
Post:	377

29 Mar 2008 21:58:21 IST

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321

Easy vectors sum...Rates assured...

None

The planes 2x-3y+z=4 and x+2y-5z=11 intersect in a line L.Then a vector parallel to L is
a)13i+11j+7k
b)13i+11j-7k
c)13i-11j+7k
d)none of these.
My method was to first eliminate z from the equations.
Then we get 11x-13y=3
Thus,x:y=11:-13
Then,eliminating x from the equations,we get -7y+11z=-18
Thus,y:z=-7:11
Thus,x:y:z=-13:11:-7
Thus,ans should be c right??
But,its given as a..What is wrong with my solution???

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Comments (1)

varsha valli g.

Blazing goIITian

Joined: 31 Jan 2007

Posts: 515

1 Apr 2008 11:23:27 IST

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just solve the 2 eqn using matrix method
x y z
-3 1 2 -3
2 -5 1 2
u will get
x/13 = y/11 = z/7
so option a)
!!!!!!!!!!!!!!!!!!!!!!!

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