Solve the following systems of linear equations by Cramer’s rule:
2x – y = – 2
3x + 4y = 3
Given : – Two equations 2x – y = – 2 and 3x + 4y = 3
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 = – 2
3x + 4y = 3
So by comparing with the theorem, let's find D, D1 and D2
Solving determinant, expanding along 1st row
⇒ D = 2(4) – (3)( – 1)
⇒ D = 8 + 3
⇒ D = 11
Again,
Solving determinant, expanding along 1st row
⇒ D1 = – 2(4) – (3)( – 1)
⇒ D1 = – 8 + 3
⇒ D1 = – 5
and
Solving determinant, expanding along 1st row
⇒ D2 = 3(2) – ( – 2)(3)
⇒ D2 = 6 + 6
⇒ D2 = 12
Thus by Cramer’s Rule, we have
⇒
⇒
and
⇒
⇒