InterviewSolution
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Find the real values of x and y, if(i) (x + iy) (2 – 3i) = 4 + i(ii) (3x – 2i y) (2 + i)2 = 10(1 + i) |
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Answer» (i) (x + iy) (2 – 3i) = 4 + i Given as (x + iy) (2 – 3i) = 4 + i Now let us simplify the expression we get, x(2 – 3i) + iy(2 – 3i) = 4 + i 2x – 3xi + 2yi – 3yi2 = 4 + i 2x + (-3x + 2y)i – 3y(-1) = 4 + i [since, i2 = -1] 2x + (-3x + 2y)i + 3y = 4 + i [since, i2 = -1] (2x + 3y) + i(-3x + 2y) = 4 + i By equating real and imaginary parts on both sides, we get 2x + 3y = 4… (i) And -3x + 2y = 1… (ii) Now multiply (i) by 3 and (ii) by 2 and add By solving we get, 6x – 6x – 9y + 4y = 12 + 2 13y = 14 y = 14/13 Then substitute the value of y in (i) we get, 2x + 3y = 4 2x + 3(14/13) = 4 2x = 4 – (42/13) = (52 - 42)/13 2x = 10/13 x = 5/13 x = 5/13, y = 14/13 Thus the real values of x and y are 5/13, 14/13 (ii) (3x – 2i y) (2 + i)2 = 10(1 + i) Given as (3x – 2i y) (2 + i)2 = 10(1 + i) (3x – 2yi) (22 + i2 + 2(2)(i)) = 10 + 10i (3x – 2yi) (4 + (-1) + 4i) = 10 + 10i [since, i2 = -1] (3x – 2yi) (3 + 4i) = 10 + 10i Now let us divide with 3 + 4i on both sides we get, (3x – 2yi) = (10 + 10i)/(3 + 4i) Then multiply and divide with (3 - 4i) = [10(3 - 4i) + 10i(3 - 4i)]/(32 – (4i)2) = [30 - 40i + 30i - 40i2]/(9 – 16i2) = [30 - 10i - 40(-1)]/(9 - 16(-1)) = [70 - 10i]/25 Then, equating real and imaginary parts on both sides we get 3x = 70/25 and -2y = -10/25 x = 70/75 and y = 1/5 x = 14/15 and y = 1/5 Thus the real values of x and y are 14/15, 1/5 |
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