Answer: x = 1.
- A x = 1
- B x = 2
- C x = 3
- D x = 4
Correct answer: A. x = 1
Explanation: det(A) = 6-1=5. D<sub>x</sub> = det([[5,1],[10,3]]) = 15-10 = 5. x = D<sub>x</sub>/det(A) = 5/5 = 1. Then y = (5-2)/3 = 1... check: y=(10-1)/3=3. 2(1)+3=5 correct, 1+9=10 correct.
Concept context
Evaluation of determinants, cofactors, adjoint, inverse of matrix, Cramer's rule and area applications. Always in board and JEE.