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 =

Let A=-2x1x1123-1. If the roots of the equation detA=0 are l,m, then l3-m3=
  1. 35
  2. -35
  3. 19
  4. -19

Solution

Given:

A=-2x1x1123-1

Also,

detA=0

⇒-2x1x1123-1=0

⇒-2-1-3-x-x-2+3x-2=0

⇒x2+5x+6=0

⇒x+2x+3=0

⇒x=-2, -3

So, l3-m3=-23--33=-8+27=19

Asked in: AP EAMCET 2022 (04 Jul Shift 2)

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