Target Exam

CUET

Subject

-- Applied Mathematics - Section B2

Chapter

Algebra

Question:

Match List-I with List-II

List-I Matrix/equations

List-II Values

(A) $\begin{bmatrix}2x+1&3y\\0&y^2-5y\end{bmatrix}=\begin{bmatrix}x+3&y^2+2\\0&-6\end{bmatrix}$

(I) $x = 2, y = -1$

(B) $\begin{bmatrix}1&2&-1\\x&0&3\\y&3&4\end{bmatrix}$ is symmetric

(II) $x = 2, y = 2$

(C) $\begin{bmatrix}x&1\end{bmatrix}\begin{bmatrix}1&0\\-2&-3\end{bmatrix}\begin{bmatrix}5&2\\0&y\end{bmatrix}=0$

(III) $x=-2, y = 2$

(D) $\begin{bmatrix}x&0\\1&1\end{bmatrix}\begin{bmatrix}x&0\\1&1\end{bmatrix}=\begin{bmatrix}4&0\\-1&y/2\end{bmatrix}$

(IV) $x = 2, y = 0$

Choose the correct answer from the options given below:

Options:

(A)-(II), (B)-(I), (C)-(IV), (D)-(III)

(A)-(I), (B)-(II), (C)-(III), (D)-(IV)

(A)-(III), (B)-(IV), (C)-(I), (D)-(II)

(A)-(IV), (B)-(III), (C)-(II), (D)-(I)

Correct Answer:

(A)-(II), (B)-(I), (C)-(IV), (D)-(III)

Explanation:

The correct answer is Option (1) → (A)-(II), (B)-(I), (C)-(IV), (D)-(III)

(A) $\begin{bmatrix} 2x+1 & 3y \\ 0 & y^2-5y \end{bmatrix} = \begin{bmatrix} x+3 & y^2+2 \\ 0 & -6 \end{bmatrix}$

Equating: $2x+1 = x+3 \Rightarrow x=2$, and $y^2-5y = -6 \Rightarrow y^2-5y+6=0 \Rightarrow (y-2)(y-3)=0 \Rightarrow y=2,3$.

Also $3y=y^2+2 \Rightarrow y^2-3y+2=0 \Rightarrow (y-1)(y-2)=0 \Rightarrow y=1,2$.

Common solution: $x=2,y=2$. Matches (II).

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(B) $\begin{bmatrix} 1 & 2 & -1 \\ x & 0 & 3 \\ y & 3 & 4 \end{bmatrix}$ is symmetric.

For symmetry: $x=2$, $y=-1$. Matches (I).

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(C) $[x\ 1]\begin{bmatrix} 1&0 \\ -2&-3 \end{bmatrix}\begin{bmatrix} 5&2 \\ 0&y \end{bmatrix}=0$

First multiply: $[x\ 1]\begin{bmatrix} 1&0 \\ -2&-3 \end{bmatrix} = [x-2,\ -3-x]$.

Now $[x-2,\ -3-x]\begin{bmatrix} 5&2 \\ 0&y \end{bmatrix} = [5(x-2),\ 2(x-2)+(-3-x)y]$

= $[5x-10,\ 2x-4-xy-3y]$

Equating to [0,0]: $5x-10=0 \Rightarrow x=2$. Second: $2(2)-4-(2)y-3y=0 \Rightarrow 4-4-5y=0 \Rightarrow -5y=0 \Rightarrow y=0$.

So solution: $x=2,y=0$. Matches (IV).

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(D) $\begin{bmatrix} x & 0 \\ 1 & 1 \end{bmatrix}\begin{bmatrix} x & 0 \\ 1 & 1 \end{bmatrix} = \begin{bmatrix} 4 & 0 \\ -1 & \frac{y}{2} \end{bmatrix}$

LHS = $\begin{bmatrix} x^2 & 0 \\ x+1 & 1 \end{bmatrix}$

Equating: $x^2=4 \Rightarrow x=±2$; $x+1=-1 \Rightarrow x=-2$; $1=\frac{y}{2} \Rightarrow y=2$.

So solution: $x=-2,y=2$. Matches (III).