Evaluate
4\sqrt{7}+5\approx 15.583005244
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12-2\sqrt{7}+6\sqrt{7}-\left(\sqrt{7}\right)^{2}
Apply the distributive property by multiplying each term of 2+\sqrt{7} by each term of 6-\sqrt{7}.
12+4\sqrt{7}-\left(\sqrt{7}\right)^{2}
Combine -2\sqrt{7} and 6\sqrt{7} to get 4\sqrt{7}.
12+4\sqrt{7}-7
The square of \sqrt{7} is 7.
5+4\sqrt{7}
Subtract 7 from 12 to get 5.
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