Evaluate
6\sqrt{5}-2\approx 11.416407865
Factor
2 {(3 \sqrt{5} - 1)} = 11.416407865
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18-6\sqrt{5}+12\sqrt{5}-4\left(\sqrt{5}\right)^{2}
Apply the distributive property by multiplying each term of 3+2\sqrt{5} by each term of 6-2\sqrt{5}.
18+6\sqrt{5}-4\left(\sqrt{5}\right)^{2}
Combine -6\sqrt{5} and 12\sqrt{5} to get 6\sqrt{5}.
18+6\sqrt{5}-4\times 5
The square of \sqrt{5} is 5.
18+6\sqrt{5}-20
Multiply -4 and 5 to get -20.
-2+6\sqrt{5}
Subtract 20 from 18 to get -2.
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