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Question
Evaluate: `|("a" - "b" - "c", 2"a", 2"a"),(2"b", "b" - "c" - "a", 2"b"),(2"c", 2"c", "c" - "a" - "b")|`
Solution
We have, `|("a" - "b" - "c", 2"a", 2"a"),(2"b", "b" - "c" - "a", 2"b"),(2"c", 2"c", "c" - "a" - "b")|`
[Applying R1 → R1 + R2 + R3]
= `|("a" + "b" + "c", "a" + "b" + "c", "a" + "b" + "c"),(2"b", "b" - "c" - "a", 2"b"),(2"c", 2"c", "c" - "a" - "b")|`
[Taking (a + b + c) common from the first row]
= `("a" + "b" + "c")|(1, 1, 1),(2"b", "b" - "c" - "a", 2"b"),(2"c", 2"c", "c" - "a" - "b")|`
[Applying C1 → C1 – C3 and C2 → C2 – C3]
= `("a" + "b" + "c")|(0, 0, 1),(0, -("a" + "b" + "c"), 2"b"),("a" + "b" + "c", "a" + "b" + "c", "c" - "a" - "b")|`
Expanding along R1,
= (a + b + c) [1 × 0 + (a + b + c)2]
= (a + b + c)3
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