The value of x for which the angle between the vectors a=xi-3j-k b=2xi+xj-k is acute and the angle between the vectors b and the axis of ordinate is obtuse are

Dear pallavi

angle between the vectors a=xi-3j-k b=2xi+xj-k is acute
so cosΘ >0
 or a.b>0
   2x² -3x +1>0

(x-1)(2x-1)>0

 x<1/2   or  x>1

angle between the vectors b and the axis  of ordinate is obtuse

so b.j<0

    x<0

 fo final solution is x<0

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