Mathematics

Problem

For

\mathbf a = (2,-1,3)

and

\mathbf b = (1,4,-2)

, the vectors

k\,\mathbf a + \mathbf b

and

\mathbf a - 2\mathbf b

are perpendicular. Determine the value of

k

. a)

-\dfrac{11}{6}

\dfrac{5}{3}

\dfrac{3}{5}

\dfrac{50}{21}