Q. 374.3( 3 Votes )

# There are two values of a which makes determinant, ,then sum of these number is

A. 4

B. 5

C. -4

D. 9

Answer :

Given

= 1 [2a^{2} – (-4)] + 2 [4a – 0] + 5 [8 – 0] = 86

= 1 [2a^{2} + 4] + 2 [4a] + 5 [8] = 86

= 2a^{2} + 4 + 8a + 40 = 86

= 2a^{2} + 8a + 44 = 86

= 2a^{2} + 8a = 42

= 2 (a^{2} + 4a) = 42

= (a^{2} + 4a) = 21

⇒ a^{2} + 4a – 21 = 0

⇒ (a + 7) (a – 3) = 0

∴ a = -7 or 3

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

Rate this question :

How useful is this solution?

We strive to provide quality solutions. Please rate us to serve you better.

Related Videos

Determinants of Matrices of different order59 mins

Determining a determinant63 mins

Types of Matrices & Properties51 mins

Interactive Quiz on Properties of Determinants43 mins

Triangular Matrices & operations on matrices58 mins

Know About finding the Adjoint & Inverse Of Matrix46 mins

Lecture on Product of Determinants58 mins

Test Yourself, Properties of Determinants30 mins

Interactive Quiz on Matrices & Determinants48 mins

Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Expertsview all courses

Dedicated counsellor for each student

24X7 Doubt Resolution

Daily Report Card

Detailed Performance Evaluation

RELATED QUESTIONS :

State True or False for the statements

The determinant is equal to zero.

Mathematics - Exemplar