Question 230171: (4-7i)(4+7i)
please solve and show work thank you
Answer by Alan3354(69443)   (Show Source):
You can put this solution on YOUR website! (4-7i)(4+7i)
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= 4*(4+7i) - 7i*(4+7i)
= 16 + 28i - 28i - 49i^2
= 16 - 49i^2
i^2 = -1
= 16 + 49
= 65
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These are similar to (a-b)*(a+b) = a^2 - b^2 EXCEPT the sign is plus.
(a - bi)*(a + bi) = a^2 + b^2
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Also, nothing is solved for, there's no variable in 65. It's only simplified.
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