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If | vec a| = | vec b | = 1 and | vec ...

If ` | vec a| = | vec b | = 1 and | vec a + vecb | = sqrt3 , ` then the value of ` (3 veca -4 vec b ).(2veca +5vec b ) ` is : a)`-21` b)` -(21)/(2)` c)` 21` d)` (21)/(2)`

A

`-21`

B

` -(21)/(2)`

C

` 21`

D

` (21)/(2)`

Text Solution

Verified by Experts

The correct Answer is:
B
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