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Prove that: |y+zzyzz+xxyxx+y| = 4xyz - Mathematics

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Question

Prove that: `|(y + z, z, y),(z, z + x, x),(y, x, x + y)|` = 4xyz

Sum

Solution

`|(y + z, z, y),(z, z + x, x),(y, x, x + y)|` 

[Applying C1 → C1 + C2 + C3]

= `|(2(y + z), z, y),(2(z + x), z + x, x),(2(y + x), x, x + y)|`

= `2|(y + z, z, y),(z + x, z + x, x),(x + y, x, x + y)|`

[Applying C1 → C1 – C2]

= `2|(y, z, y),(0, z + x, x),(y, x, x + y)|`

[Applying C3 → C3 – C1]

= `2|(y, z, 0),(0, z + x, x),(y, x, x)|` 

[Applying R3 → R3 – R1]

= `2|(y, z, 0),(0, z + x, x),(y, x - z, x)|` 

= `2y[(z + x)x - x(x - z)]`

= `2y[2xz]`

= 4xyz

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Chapter 4: Determinants - Exercise [Page 77]

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NCERT Exemplar Mathematics [English] Class 12
Chapter 4 Determinants
Exercise | Q 8 | Page 77

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