Question

Let x₀ be the point of local maxima of f(x) = vector(a.(b x c)), where vector a = xi - 2j + 3k, vector b = -2i + xj - k and vector c = 7i - 2j + xk. Then the value of vector(a.b + b.c + c.a) at x = x₀ is : 

(1) –30 

(2) 14 

(3) –4 

(4) –22

Answer 1

Answer is (4) -22