Let A = [1&a(b+c)&bc 1&b(c+a)&ca 1&c(a+b)&ab] , then det A is

Question

Let A = [1&a(b+c)&bc 1&b(c+a)&ca 1&c(a+b)&ab] , then det A is (A) 0 (B) ab + bc + ca (C) I + ab + bc + ca (D) none of these.

Tardigrade Admin · Accepted Answer

Operate C2 → C2 + C3 and take out ab + bc + ac from C2. It will be found that C1 = C2

Q. Let $A = ⎣ ⎡ 111 a (b + c) b (c + a) c (a + b) b c c a ab ⎦ ⎤$ , then det A is