Evaluate
2\left(\sqrt{7}+4\right)\approx 13.291502622
Expand
2 \sqrt{7} + 8 = 13.291502622
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\left(\sqrt{7}\right)^{2}+2\sqrt{7}+1
Use binomial theorem \left(a+b\right)^{2}=a^{2}+2ab+b^{2} to expand \left(\sqrt{7}+1\right)^{2}.
7+2\sqrt{7}+1
The square of \sqrt{7} is 7.
8+2\sqrt{7}
Add 7 and 1 to get 8.
\left(\sqrt{7}\right)^{2}+2\sqrt{7}+1
Use binomial theorem \left(a+b\right)^{2}=a^{2}+2ab+b^{2} to expand \left(\sqrt{7}+1\right)^{2}.
7+2\sqrt{7}+1
The square of \sqrt{7} is 7.
8+2\sqrt{7}
Add 7 and 1 to get 8.
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