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If (x+iy)13 = a + ib, where x, y, a, b ∈ R, show that xa-yb = –2(a2 + b2) - Mathematics

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प्रश्न

If `(x + iy)^(1/3)` = a + ib, where x, y, a, b ∈ R, show that `x/a - y/b` = –2(a2 + b2)

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उत्तर

`(x + iy)^(1/3)` = a + ib

⇒ x + iy = (a + ib)3

i.e., x + iy = a3 + i3 b3 + 3iab (a + ib)

= a3 – ib3 + i3a2b – 3ab2

= a3 – 3ab2 + i(3a2b – b3)

⇒ x = a3 – 3ab2 and y = 3a2b – b3

Thus `x/a = a^2 - 3b^2` and `y/b = 3a^2 - b^2`

So, `x/a - y/b = a^2 - 3b^2 + b^2`

= `-2a^2 - 2b^2`

= –2(a2 + b2)

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अध्याय 5: Complex Numbers and Quadratic Equations - Solved Examples [पृष्ठ ७८]

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एनसीईआरटी एक्झांप्लर Mathematics [English] Class 11
अध्याय 5 Complex Numbers and Quadratic Equations
Solved Examples | Q 2 | पृष्ठ ७८

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