Using elementary transformations, find the inverse of matrix [1327], if it exists.
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Solution
Let A=[1327]
We know that A=IA ⇒[1327]=[1001]A
Applying R2→R2−2R1 ⇒[132−27−6]=[100−21−0]A ⇒[1301]=[10−21]A
Applying R1→R1−3R2 ⇒[1−3(0)3−3(1)01]=[1−(−2×3)0−1(3)−21]A ⇒[1001]=[7−3−21]A
This is similar to I=A−1A
Thus, A−1=[7−3−21]