Evaluate
67-12\sqrt{7}\approx 35.250984267
Expand
67-12\sqrt{7}
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9\left(\sqrt{7}\right)^{2}-12\sqrt{7}+4
Use binomial theorem \left(a-b\right)^{2}=a^{2}-2ab+b^{2} to expand \left(3\sqrt{7}-2\right)^{2}.
9\times 7-12\sqrt{7}+4
The square of \sqrt{7} is 7.
63-12\sqrt{7}+4
Multiply 9 and 7 to get 63.
67-12\sqrt{7}
Add 63 and 4 to get 67.
9\left(\sqrt{7}\right)^{2}-12\sqrt{7}+4
Use binomial theorem \left(a-b\right)^{2}=a^{2}-2ab+b^{2} to expand \left(3\sqrt{7}-2\right)^{2}.
9\times 7-12\sqrt{7}+4
The square of \sqrt{7} is 7.
63-12\sqrt{7}+4
Multiply 9 and 7 to get 63.
67-12\sqrt{7}
Add 63 and 4 to get 67.
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