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Find the following as a single complex number x + iy:(i) (5 + 9 i) (-3 + 4 i)(ii) (-2 - 5 i) (3 - 6 i) |
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Answer» (i) (5 + 9 i) (-3 + 4 i) = 5(-3 + 4 i ) +9 i(-3 + 4 i) = -15 + 20 i -27 i +36 i2 = -15 - 7 i - 36 = -51 - 7 i = x = -51 y = -7 (II) (-2 - 5 i) (3 - 6 i) = -2(3 - 6 i) -5 i(3 - 6 i) = -6 + 12 i - 15 i + 30 i2 = -6 -3 i +30 = 24 - 3 i = x = 24 y = -3 |
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