SOLUTION: what is the equivalent to (6+3i)(6-3i) and how would u work it out??????

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Question 540696: what is the equivalent to (6+3i)(6-3i) and how would u work it out??????
Found 2 solutions by mananth, josmiceli:
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
(6+3i)(6-3i)
(a+b)(a-b)=a^2-b^2
(6+3i)(6-3i)=36-9i^2
36 -9*(sqrt(-1)^2)
36-(9*-1)
36+9
=45

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
You have to use the rule +i%5E2+=+-1+
+%28+6+%2B+3i+%29%2A%28+6+-+3i+%29++=+36+%2B+3%2A6%2Ai+-+3%2A6%2Ai++-+3%2A3%2Ai%5E2+
+%28+6+%2B+3i+%29%2A%28+6+-+3i+%29++=+36+%2B+18i+-+18i+-+9%2A%28-1%29+
+%28+6+%2B+3i+%29%2A%28+6+-+3i+%29++=+36+%2B+9+
+%28+6+%2B+3i+%29%2A%28+6+-+3i+%29++=+45+