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(sqrt3+i)^100=2^99(p+iq) then p and q ar...

`(sqrt3+i)^100=2^99(p+iq)` then p and q are the roots of which of the following quadratic equation?

A

`x^2-(sqrt3+1)x-sqrt3=0`

B

`x^2-(sqrt3-1)x-sqrt3=0`

C

`x^2+(sqrt3+1)x+sqrt3=0`

D

None

Text Solution

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The correct Answer is:
To solve the equation \((\sqrt{3} + i)^{100} = 2^{99}(p + iq)\) and find the quadratic equation for which \(p\) and \(q\) are the roots, we can follow these steps: ### Step 1: Express \(\sqrt{3} + i\) in polar form First, we find the modulus and argument of \(\sqrt{3} + i\): - The modulus is given by: \[ r = \sqrt{(\sqrt{3})^2 + (1)^2} = \sqrt{3 + 1} = \sqrt{4} = 2 \] - The argument \(\theta\) can be calculated using: \[ \theta = \tan^{-1}\left(\frac{1}{\sqrt{3}}\right) = \frac{\pi}{6} \] Thus, we can express \(\sqrt{3} + i\) in polar form as: \[ \sqrt{3} + i = 2\left(\cos\frac{\pi}{6} + i\sin\frac{\pi}{6}\right) = 2e^{i\frac{\pi}{6}} \] ### Step 2: Raise to the power of 100 Now, we raise this expression to the power of 100: \[ (\sqrt{3} + i)^{100} = (2e^{i\frac{\pi}{6}})^{100} = 2^{100}e^{i\frac{100\pi}{6}} = 2^{100}e^{i\frac{50\pi}{3}} \] ### Step 3: Simplify the argument Next, we simplify the argument \(\frac{50\pi}{3}\): \[ \frac{50\pi}{3} = 16\pi + \frac{2\pi}{3} = 2\cdot 8\pi + \frac{2\pi}{3} \] Since \(e^{i(2k\pi + \theta)} = e^{i\theta}\), we have: \[ e^{i\frac{50\pi}{3}} = e^{i\frac{2\pi}{3}} \] ### Step 4: Substitute back into the equation Substituting back, we get: \[ (\sqrt{3} + i)^{100} = 2^{100} e^{i\frac{2\pi}{3}} = 2^{100}\left(\cos\frac{2\pi}{3} + i\sin\frac{2\pi}{3}\right) \] Calculating \(\cos\frac{2\pi}{3}\) and \(\sin\frac{2\pi}{3}\): \[ \cos\frac{2\pi}{3} = -\frac{1}{2}, \quad \sin\frac{2\pi}{3} = \frac{\sqrt{3}}{2} \] Thus, \[ (\sqrt{3} + i)^{100} = 2^{100}\left(-\frac{1}{2} + i\frac{\sqrt{3}}{2}\right) = 2^{99}(-1 + i\sqrt{3}) \] ### Step 5: Compare with the original equation From the equation \((\sqrt{3} + i)^{100} = 2^{99}(p + iq)\), we can equate: \[ p + iq = -1 + i\sqrt{3} \] This gives us: \[ p = -1, \quad q = \sqrt{3} \] ### Step 6: Form the quadratic equation To find the quadratic equation whose roots are \(p\) and \(q\), we use the formula: \[ x^2 - (p + q)x + pq = 0 \] Calculating the sum and product of the roots: \[ p + q = -1 + \sqrt{3}, \quad pq = (-1)(\sqrt{3}) = -\sqrt{3} \] Thus, the quadratic equation is: \[ x^2 - (-1 + \sqrt{3})x - \sqrt{3} = 0 \] This can be rearranged to: \[ x^2 - (1 - \sqrt{3})x - \sqrt{3} = 0 \] ### Final Answer The quadratic equation for which \(p\) and \(q\) are the roots is: \[ x^2 - (1 - \sqrt{3})x - \sqrt{3} = 0 \]
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