Question 63374
(√[3] + 4√[5]) * (2√[3] – √[5])
Use FOIL:
F: (sqrt3)(2sqrt3)=6
O: (sqrt3)(-sqrt5)=-sqrt15
I: (4sqrt5)(2sqrt3)=8sqrt15
L: (4sqrt5)(-sqrt5)=-20
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Add them up to get:
-14+7sqrt15
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Cheers,
Stan H.