# NCERT Class 12-Mathematics: Exemplar Chapter – 4 Determinants Part 10 (For CBSE, ICSE, IAS, NET, NRA 2022)

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**Question 19**:

Using matrix method, solve the system of equations , and .

**Answer**:

Given system of equation is

In the form of

For

Now,

**Question 20**:

Given , find BA and use this to solve the system of equations .

**Answer**:

We have,

Also,

**Question 21**:

If and , then prove that .

**Answer**:

Let

Applying , we get

Taking common from the first column, we get

Now, Expanding along , we get

Given that

But it is given that

Hence Proved