# There are two values of a which makes determinant, ,then sum of these number isA. 4B. 5C. -4D. 9

Given  = 1 [2a2 – (-4)] + 2 [4a – 0] + 5 [8 – 0] = 86

= 1 [2a2 + 4] + 2 [4a] + 5  = 86

= 2a2 + 4 + 8a + 40 = 86

= 2a2 + 8a + 44 = 86

= 2a2 + 8a = 42

= 2 (a2 + 4a) = 42

= (a2 + 4a) = 21

a2 + 4a – 21 = 0

(a + 7) (a – 3) = 0

a = -7 or 3

Sum of these numbers is -7 + 3 = -4. [Option (C)]

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