1. (a) Find conjugate and magnitude of \( z=\frac{(3+2 i)(1-2 i)}{4+3 i} \) (To be solved in elass) (b) If \( = \) is a complex number then \( |z| \geq 0 \) and \( |z|=0 \) iff \( z=0 \) (To be solved in class) \( z=3(1-2 i)+2 i(1-2 i) \)
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To find the conjugate and magnitude of \( z=\frac{(3+2 i)(1-2 i)}{4+3 i} \), we first compute the numerator and denominator separately. The numerator becomes \((3+2i)(1-2i) = 3 - 6i + 2i + 4 = 7 - 4i\). The denominator remains as \(4 + 3i\). Now, we can express \(z\) in standard form: \[ z = \frac{(7-4i)(4-3i)}{(4+3i)(4-3i)} = \frac{(28 - 21i - 16i + 12)}{16 + 9} = \frac{40 - 37i}{25} = \frac{40}{25} - \frac{37}{25}i = \frac{8}{5} - \frac{37}{25}i \] The conjugate of \(z\) is \(\frac{8}{5} + \frac{37}{25}i\) and the magnitude is \(|z| = \sqrt{(\frac{8}{5})^2 + (-\frac{37}{25})^2} = \sqrt{\frac{64}{25} + \frac{1369}{625}} = \sqrt{\frac{1600}{625}} = \frac{40}{25} = \frac{8}{5}\). Now onto the evaluation of \(z=3(1-2 i)+2 i(1-2 i)\): First, calculate \(3(1-2i) = 3 - 6i\) and \(2i(1-2i) = 2i - 4i^2 = 2i + 4 = 4 + 2i\). Adding these results gives: \[ z = (3 - 6i) + (4 + 2i) = (3 + 4) + (-6i + 2i) = 7 - 4i. \] Voila! We've got \(z = 7 - 4i\). Now, you can explore more about the delightful world of complex numbers and their applications in engineering and physics.