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The modulus of \newline1i3+i+4i5\frac{1-i}{3+i}+\frac{4i}{5} is\newline(A) 5\sqrt{5} unit\newline(B) 115\frac{\sqrt{11}}{5} unit\newline(C) 55\frac{\sqrt{5}}{5} unit\newline(D) 125\frac{\sqrt{12}}{5} unit

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Q. The modulus of \newline1i3+i+4i5\frac{1-i}{3+i}+\frac{4i}{5} is\newline(A) 5\sqrt{5} unit\newline(B) 115\frac{\sqrt{11}}{5} unit\newline(C) 55\frac{\sqrt{5}}{5} unit\newline(D) 125\frac{\sqrt{12}}{5} unit
  1. Simplify Expression: First, we need to simplify the expression (1i)/(3+i)(1-i)/(3+i). To do this, we multiply the numerator and the denominator by the conjugate of the denominator to remove the imaginary part from the denominator.\newline(1i)/(3+i)(3i)/(3i)=(3i3i+i2)/(9i2)(1-i)/(3+i) \cdot (3-i)/(3-i) = (3 - i - 3i + i^2)/(9 - i^2)
  2. Numerator and Denominator Simplification: Simplify the numerator and denominator of the resulting fraction. \newline(3i3i+i2)/(9i2)=(34i1)/(9+1)=(24i)/10=1525i(3 - i - 3i + i^2)/(9 - i^2) = (3 - 4i - 1)/(9 + 1) = (2 - 4i)/10 = \frac{1}{5} - \frac{2}{5}i
  3. Addition of Terms: Now, we add the second term (4i5)(\frac{4i}{5}) to the simplified first term.(1525i)+45i=15+25i(\frac{1}{5} - \frac{2}{5}i) + \frac{4}{5}i = \frac{1}{5} + \frac{2}{5}i
  4. Modulus Calculation: To find the modulus of the complex number 15+(25)i\frac{1}{5} + \left(\frac{2}{5}\right)i, we use the formula for the modulus of a complex number a+bia + bi, which is a2+b2\sqrt{a^2 + b^2}. \newlineModulus = (15)2+(25)2=125+425=525\sqrt{\left(\frac{1}{5}\right)^2 + \left(\frac{2}{5}\right)^2} = \sqrt{\frac{1}{25} + \frac{4}{25}} = \sqrt{\frac{5}{25}}
  5. Final Modulus Simplification: Simplify the square root to find the modulus. 525=15=15=15=55\sqrt{\frac{5}{25}} = \sqrt{\frac{1}{5}} = \frac{\sqrt{1}}{\sqrt{5}} = \frac{1}{\sqrt{5}} = \frac{\sqrt{5}}{5}

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