Let A = - 2 x 1 x 1 1 2 3 - 1 . If the roots of the equation det A = 0 are l , m , then l 3 - m 3 =

Question

Let A = - 2 x 1 x 1 1 2 3 - 1 . If the roots of the equation det A = 0 are l , m , then l 3 - m 3 =, 35, - 35, 19, - 19

MARKS App · Accepted Answer

Given: A = - 2 x 1 x 1 1 2 3 - 1 Also, det A = 0 ⇒ - 2 x 1 x 1 1 2 3 - 1 = 0 ⇒ - 2 - 1 - 3 - x - x - 2 + 3 x - 2 = 0 ⇒ x 2 + 5 x + 6 = 0 ⇒ x + 2 x + 3 = 0 ⇒ x = - 2 , - 3 So, l 3 - m 3 = - 2 3 - - 3 3 = - 8 + 27 = 19

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