# Don't Guess The Possible value,Calculate it

Level pending**a** and **b** are vectors such that **| a+b |** = √29 and **a**×(2**i**+3**j**+4**k**) =(2**i**+3**j**+4**k**)×**b** ,then a possible value of (**a**+**b**).(-7**i**+2**j**+3**k**) is

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