मराठी

Show that i(-1+3i)3 is a real number. - Mathematics and Statistics

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प्रश्न

Show that `(-1 + sqrt(3)"i")^3` is a real number.

बेरीज

उत्तर

`(-1 + sqrt(3)"i")^3`

= `(-1)^3 + 3(-1)^2 (sqrt(3)"i") + 3(-1) (sqrt(3)"i")^2 + (sqrt(3)"i")^3`  ...[(a + b)3 = a3 + 3a2b + 3ab2 + b3]

= `- 1 + 3sqrt(3)"i" - 3(3"i"^2) + 3sqrt(3)"i"^3`

= `-1 + 3sqrt(3)"i" - 3(-3) - 3sqrt(3)"i"`   ...[∵ i2 = –1, i3 = – i]

= – 1 + 9

= 8, which is a real number.

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Conjugate of a Complex Number
  या प्रश्नात किंवा उत्तरात काही त्रुटी आहे का?
पाठ 3: Complex Numbers - EXERCISE 3.1 [पृष्ठ ३८]

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