# NCERT Class 12-Mathematics: Exemplar Chapter –3 Matrices Part 14

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**Question 37:**

Find inverse, by elementary row operations (if possible), of the following matrices

(i)

(ii)

**Answer:**

(i) Let

In order to use elementary row operations we may write .

where B is the inverse of A

(ii) Let

In order to use elementary row operations, we write

Since, we obtain all zeroes in a row of the matrix A on LHS, so dose not exist.

**Question 38:**

If , then find values of .

**Answer:**

As the matrices are equal. So corresponding elements of both the matrix must also hold the equality.

Hence, we get:

When

And when

Thus,

; or ; and …ans

**Question 39:**

If , Find a matrix C such that is a null matrix.

**Answer:**

We have,

Let

Also,

And