1.

If 2a+3b+c=0, " then " axx b +b xx c+c xx a is equal to

Answer»

`6(bxxc)`
`3(bxxc)`
`2(bxxc)`
0

Solution :Given , `2a+3b+c=0`
`RARR 2a+3b=-c`
Taking cross product with a and b respectively, we GET
`2(axxa)+3(AXXB)=axxc`
`rArr 3(axxb)=cxxa` .....(ii)
and `2(bxxa)+3(bxxb)=-bxxc`
`rArr 2(axxb)=bxxc` ......(ii)
Now , `axxb+bxxc+cxxa`
`=axxb+bxxc+3(axxb)`
`=4(axxb)+bxxc`
`=2(bxxc)+bxxc`
`=3(bxxc)` .


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