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Please Solve RD Sharma Class 12 Chapter Algebra of Matrices Exercise 4.2 Question 15 Subquestion (iii) Maths Textbook Solution.

Answers (1)

Answer: x = 1, y = 2
Hint: Solve LHS part and then equate with RHS part.
Given:

x \begin{bmatrix} 2\\1 \end{bmatrix} + y \begin{bmatrix} 3\\5 \end{bmatrix} +\begin{bmatrix} -8\\11 \end{bmatrix} = 0
Here, we have to compute x  and y .
Solution:

x \begin{bmatrix} 2\\1 \end{bmatrix} + y \begin{bmatrix} 3\\5 \end{bmatrix} +\begin{bmatrix} -8\\11 \end{bmatrix} = 0

\begin{bmatrix} 2x+3y-8\\x+5y-11 \end{bmatrix} = \begin{bmatrix} 0\\0 \end{bmatrix}

Equating this, we get:

2x+3y-8 = 0
\Rightarrow 2x+3y=8                                                                                      …(1)                                                                                  

Also,

x+5y-11 = 0
\Rightarrow x=11-5y                                                                                      …(2)                                                    
Applying the value of ‘x ’ in equation (1), we get:

2(11 -5y) + 3y = 8
22 -10y + 3y = 8
-7y = 8 -22
-7y = -14
y = 2

Applying the value of ‘y’ in equation (2), we get:

x = 11 - 5(2)
x = 11- 10
x = 1

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