# Solve the followi

Given: - Two equations 2x – y = 1 and 7x – 2y = – 7

Tip: - Theorem – Cramer’s Rule

Let there be a system of n simultaneous linear equations and with n unknown given by     and let Dj be the determinant obtained from D after replacing the jth column by Then, provided that D ≠ 0

Now, here we have

2x – y = 1

7x – 2y = – 7

So by comparing with the theorem, let's find D, D1 and D2 Solving determinant, expanding along 1st row

D = 2( – 2) – (7)( – 1)

D = – 4 + 7

D = 3

Again, Solving determinant, expanding along 1st row

D1 = 1( – 2) – ( – 7)( – 1)

D1 = – 2 – 7

D1 = – 9

and Solving determinant, expanding along 1st row

D2 = 2( – 7) – (7)(1)

D2 = – 14 – 7

D2 = – 21

Thus by Cramer’s Rule, we have  x = – 3

and  y = – 7

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