Find a 2 × 2 matrix A such that
Given A is a 2×2 matrix,
So let
Here I2 is an identity matrix of size 2,
So the given equation becomes,
To satisfy the above equality condition, corresponding entries of the matrices should be equal, i.e.,
a + b = 6…….(i)
– 2a + 4b = 0 ⇒ 2a = 4b ⇒ a = 2b……..(ii)
c + d = 0 ⇒ c = – d……(iii)
– 2c + 4d = 6 ……(iv)
Substitute the values of eqn(ii) in eqn (i), we get
a + b = 6 ⇒ 2b + b = 6 ⇒ b = 2
So eqn(ii) becomes, a = 2b = 2(2) = 4⇒ a = 4
Substitute the values of eqn(iii) in eqn (iv), we get
– 2c + 4d = 6 ⇒ – 2( – d) + 4d = 6 ⇒ 2d + 4d = 6 ⇒ 6d = 6 ⇒ d = 1
So eqn(iii) becomes, c = – d⇒ c = – 1
Now substituting these values in matrix A, we get
is the matrix A.