Using elementary transformations, find the inverse of matrix [2513], if it exists.
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Solution
Let A=[2513]
We know that A=IA ⇒[2513]=[1001]A
Applying R1→R1−R2 ⇒[2−15−313]=[1−00−101]A ⇒[1213]=[1−101]A
Applying R2→R2−R1 ⇒[121−13−2]=[1−10−11−(−1)]A ⇒[1201]=[1−1−12]A
Applying R1→R1−2R2 ⇒[1−2(0)2−2(1)01]=[1−2(−1)−1−2(2)−12]A ⇒[1001]=[3−5−12]A ⇒I=[3−5−12]A
This is similar to I=A−1A
Thus, A−1=[3−5−12]