The maximum value of “a” such that the matrix has three linearly in...
The characteristic equation of A is
|A-XI| = 0
⇒ f(x) = x3 + 6x2 + 11x + 6 + 2a
= (x + 1)(x + 2)(x + 3)+2a = 0
f(x) cannot have all 3 real roots (if any) equal
for if f(x) = (x-k)3, then comparing coefficients, we get
6 = –3k, 3k2 = 11
No such k exists
A) Thus f(x) = 0 has repeated (2) roots α, α, β
or
B) f(x) = 0 has real roots (distance) α, β, δ
Now
At x1, f(x) has relative maximum
At x2, f(x) has relative minimum
The graph of f(x) will be as below
Case A. repeated roots (α, α, β)
Case B. distinct roots
Note that the graph of f(x) cannot be like the one given below
Thus in all possible cares we have