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Using properties of determinants, show that |a+babaa+ccbcb+c| = 4abc. - Mathematics and Statistics

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प्रश्न

Using properties of determinants, show that `|("a" + "b", "a", "b"),("a", "a" + "c", "c"),("b", "c", "b" + "c")|` = 4abc.

योग

उत्तर

L.H.S. = `|("a" + "b", "a", "b"),("a", "a" + "c", "c"),("b", "c", "b" + "c")|`

Applying C1 → C1 – (C2 + C3), we get

L.H.S. = `|(0, "a", "b"),(-2"c", "a" + "c", "c"),(-2"c", "c", "b" + "c")|`

Taking (– 2) common from C1, we get

L.H.S. = ` - 2|(0, "a", "b"),("c", "a" + "c", "c"),("c", "c", "b" + "c")|`

Applying C2 → C2 – C1 and C3 → C3 – C1, we get

L.H.S. = `-2|(0, "a", "b"),("c", "a", 0),("c", 0, "b")|`

= - 2[0(ab – 0) – a(bc – 0) + b(0 – ac)]
= – 2(0 – abc – abc)
= – 2(– 2abc)
= 4abc
= R.H.S.

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अध्याय 6: Determinants - EXERCISE 6.2 [पृष्ठ ८९]

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बालभारती Mathematics and Statistics 1 (Commerce) [English] 11 Standard Maharashtra State Board
अध्याय 6 Determinants
EXERCISE 6.2 | Q 2) | पृष्ठ ८९

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