मराठी

Find the value of: x3 – x2 + x + 46, if x = 2 + 3i

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प्रश्न

Find the value of: x3 –  x2 + x + 46, if x = 2 + 3i

बेरीज
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उत्तर

x = 2 + 3i

∴ x – 2 = 3i

∴ `(x - 2)^2 = (3i)^2`

∴ (x – 2)2 = 9i2

∴ x2 – 4x + 4 = 9(– 1)      ...[∵ i2 = – 1]

∴ x2 – 4x + 13 = 0         ...(i)

                        x + 3
`x^2 – 4x + 13")"overline(x^3 - x^2 + x + 46)"`
                      x3 – 4x2 + 13x
                      –    +    –                 
                             3x2 – 12x + 46
                             3x2 – 12x + 39
                          –       +        –      
                                                 7
∴x3 – x2 + x + 46

= (x2 – 4x + 13)(x + 3) + 7

= 0(x + 3) + 7    ...[From (i)]

= 7.

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पाठ 3: Complex Numbers - EXERCISE 3.1 [पृष्ठ ३८]

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