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If [x−y0x+y1]\begin{bmatrix} x-y & 0 \\ x+y & 1 \end{bmatrix} is an identity matrix and [xyzx]\begin{bmatrix} x & y \\ z & x \end{bmatrix} is a singular matrix then:

Solution

✅ Correct Option: 1

An identity matrix has the form [1001]\begin{bmatrix} 1 & 0 \\ 0 & 1 \end{bmatrix}.

Since [x−y0x+y1]\begin{bmatrix} x-y & 0 \\ x+y & 1 \end{bmatrix} is an identity matrix:

x−y=1x - y = 1 ... (1)

x+y=0x + y = 0 ... (2)


Adding equations (1) and (2):

x−y+x+y=1+0x - y + x + y = 1 + 0

2x=12x = 1

x=12x = \frac{1}{2}

From equation (2):

12+y=0\frac{1}{2} + y = 0

y=−12y = -\frac{1}{2}


A matrix is singular when its determinant equals 0.

For the matrix [xyzx]\begin{bmatrix} x & y \\ z & x \end{bmatrix}, the determinant is:

Det=x2−yz\text{Det} = x^2 - yz

Since the matrix is singular:

x2−yz=0x^2 - yz = 0

x2=yzx^2 = yz


Substituting x=12x = \frac{1}{2} and y=−12y = -\frac{1}{2}:

(12)2=(−12)⋅z\left(\frac{1}{2}\right)^2 = \left(-\frac{1}{2}\right) \cdot z

14=−z2\frac{1}{4} = -\frac{z}{2}

z=−12z = -\frac{1}{2}


The values are:

x=12x = \frac{1}{2}

y=−12y = -\frac{1}{2}

z=−12z = -\frac{1}{2}

Therefore: x>y=zx > y = z

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