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

The values of $\lambda$ and $\mu$ such that the system of equations $x + y + z = 6$, $3x + 5y + 5z = 26$, $x + 2y + \lambda z = \mu$ has no solution, are :

  1. A $\lambda$ = 3, $\mu$ = 5
  2. B $\lambda$ = 3, $\mu$ $\ne$ 10
  3. C $\lambda$ $\ne$ 2, $\mu$ = 10
  4. D $\lambda$ = 2, $\mu$ $\ne$ 10 Correct answer

Solution

$x + y + z = 6$ ..... (i)<br><br>$3x + 5y + 5z = 26$ .... (ii)<br><br>$x + 2y + \lambda z = \mu$ ..... (iii)<br><br>$5 \times (i) - (ii) \Rightarrow 2x = 4 \Rightarrow x = 2$<br><br>$\therefore$ from (i) and (iii)<br><br>$y + z = 4$ ..... (iv)<br><br>$2y + \lambda z = \mu - 2$ .....(v)<br><br>$(v) - 2 \times (iv)$<br><br>$\Rightarrow (\lambda - 2)z = \mu - 10$<br><br>$\Rightarrow z = {{\mu - 10} \over {\lambda - 2}}$ &amp; $y = 4 - {{\mu - 10} \over {\lambda - 2}}$<br><br>$\therefore$ For no solution $\lambda$ = 2 and $\mu$ $\ne$ 10.

About this question

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

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