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Show that (7+i37-i3+7-i37+i3) is real

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प्रश्न

Show that `((sqrt(7) + "i"sqrt(3))/(sqrt(7) - "i"sqrt(3)) + (sqrt(7) - "i"sqrt(3))/(sqrt(7) + "i"sqrt(3)))` is real

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उत्तर

`((sqrt(7) + sqrt(3)"i")/(sqrt(7) - sqrt(3)"i") + (sqrt(7) - sqrt(3)"i")/(sqrt(7) + sqrt(3)"i"))`

= `[((sqrt(7) + sqrt(3)"i")^2 + (sqrt(7) - sqrt(3)"i")^2)/((sqrt(7) -sqrt(3)"i")(sqrt(7) + sqrt(3)"i"))]`

= `(7 + 2sqrt(21)"i" + 3"i"^2 + 7 - 2sqrt(21)"i" + 3"i"^2)/(7 - 3"i"^2)`

= `(7 + 3(-1) + 7 + 3(-1))/(7 - 3(-1)`   ...[∵ i2 = – 1]

= `(7 - 3 + 7 - 3)/(7 + 3)`

= `8/10`

= `4/5`

which is a real number

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  क्या इस प्रश्न या उत्तर में कोई त्रुटि है?
अध्याय 1: Complex Numbers - Exercise 1.1 [पृष्ठ ६]

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