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November 23, 2014

November 23, 2014

Posted by **Kim** on Wednesday, March 25, 2009 at 2:29pm.

(2-3i)(5i) over 2+3i

Please help!! I do not understand this.

- Pre-Cal -
**Reiny**, Wednesday, March 25, 2009 at 3:52pm(2-3i)(5i) over 2+3i

= 5i(2-3i)/(2+3i)

multiply top and bottom by 2-3i

= 5i(4 - 12i + 9i^2)/(4-9i^2)

= 5i(-13 - 12i)/13

= (-65i - 60i^2)/13

= (60 - 65i)/13

or 60/13 - 5i if by standard form you mean a + bi

- oops arithmetic error Pre-Cal -
**Reiny**, Wednesday, March 25, 2009 at 4:00pmok, Kim ,I messed up in the arithmetic

but, if you understand what I did, you should be able to fix it yourself.

hint: the error is from

= 5i(4 - 12i + 9i^2)/(4-9i^2) to

= 5i(-13 - 12i)/13

- Pre-Cal -
**YOU'RE BAD AT MATH**, Sunday, May 13, 2012 at 2:27pmYOU SHOULD KNOW HOW TO DO THIS!

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