Medium MCQ +4 / -1 PYQ · JEE Mains 2021

The values of a and b, for which the system of equations

2x + 3y + 6z = 8

x + 2y + az = 5

3x + 5y + 9z = b

has no solution, are :

  1. A a = 3, b $\ne$ 13 Correct answer
  2. B a $\ne$ 3, b $\ne$ 13
  3. C a $\ne$ 3, b = 3
  4. D a = 3, b = 13

Solution

$$D = \left| {\matrix{ 2 &amp; 3 &amp; 6 \cr 1 &amp; 2 &amp; a \cr 3 &amp; 5 &amp; 9 \cr } } \right| = 3 - a$$<br><br>$$D = \left| {\matrix{ 2 &amp; 3 &amp; 8 \cr 1 &amp; 2 &amp; 5 \cr 3 &amp; 5 &amp; b \cr } } \right| = b - 13$$<br><br>If a = 3, b $\ne$ 13, no solution.

About this question

Subject: Mathematics · Chapter: Matrices and Determinants · Topic: Types of Matrices and Operations

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