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# Complex Numbers

0
23
1

If Q = 11 - 5i, E = 11i, and D = 2i + 3, find Q*E*D.

May 3, 2022

#1
+9310
+1

You can multiply out just like "i" was a variable instead of sqrt(-1), and then use i^2 = -1 occasionally.

$$\quad Q\times E \times D\\ = (11- 5i)(11i)(2i + 3)\\ = (121i - 55i^2)(2i + 3)\\ = (55 + 121i)(2i + 3)$$

Can you expand the rest?

May 3, 2022