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Let Δ = apbqcr|apxbqycrz| = 16, then Δ1 = paapqbbqrccr|p+xa+xa+pq+yb+yb+qr+zc+zc+r| = 32. - Mathematics

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Question

Let Δ = `|("a", "p", x),("b", "q", y),("c", "r", z)|` = 16, then Δ1 = `|("p" + x, "a" + x, "a" + "p"),("q" + y, "b" + y, "b" + "q"),("r" + z, "c" + z, "c" + "r")|` = 32.

Options

  • True

  • False

MCQ
True or False
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Solution

This statement is True.

Explanation:

Given that Δ = `|("a", "p", x),("b", "q", y),("c", "r", z)|` = 16

L.H.S. Δ1 = `|("p" + x, "a" + x, "a" + "p"),("q" + y, "b" + y, "b" + "q"),("r" + z, "c" + z, "c" + "r")|`

C1 → C1 + C2 + C3

= `|("2p" + 2x + 2"a", "a" + x, "a" + "p"),(2"q" +2y + 2"b", "b" + y, "b" + "q"),(2"r" + 2z + 2"c", "c" + z, "c" + "r")|`

= `2|("p" + x + "a", "a" + x, "a" + "p"),("q" +y + "b", "b" + y, "b" + "q"),("r" + z + "c", "c" + z, "c" + "r")|`  ......[Taking 2 common from C1]

C1 → C1 – C2 = `2|("p", "a" + x, "a" + "p"),("q", "b" + y, "b" + "q"),("r", "c" + z, "c" + "r")|`

C3 → C3 – C2d = `2|("p", "a" + x, "a"),("q", "b" + y, "b"),("r", "c" + z, "c")|`

Splitting up C2

= `2|("p", "a", "a"),("q", "b", "b"),("r", "c", "c")| + 2|("p", x, "a"),("q", "y", "b"),("r", "z", "c")|`

= `2(0) + 2|("p", x, "a"),("q", y, "b"),("r", z, "c")|`

= `2|("p", x, "a"),("q", y, "b"),("r", z, "c")|`

⇒ `2|("a", "p", x),("b", "q", y),("c", "r", z)|`  ......(C1 ↔ C3 and C2 ↔ C3)

= 2 × 16

= 32

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Chapter 4: Determinants - Exercise [Page 85]

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NCERT Exemplar Mathematics [English] Class 12
Chapter 4 Determinants
Exercise | Q 57 | Page 85

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