Evaluate
17-2\sqrt{70}\approx 0.266799469
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17-2\sqrt{70}
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\left(\sqrt{7}\right)^{2}-2\sqrt{7}\sqrt{10}+\left(\sqrt{10}\right)^{2}
Use binomial theorem \left(a-b\right)^{2}=a^{2}-2ab+b^{2} to expand \left(\sqrt{7}-\sqrt{10}\right)^{2}.
7-2\sqrt{7}\sqrt{10}+\left(\sqrt{10}\right)^{2}
The square of \sqrt{7} is 7.
7-2\sqrt{70}+\left(\sqrt{10}\right)^{2}
To multiply \sqrt{7} and \sqrt{10}, multiply the numbers under the square root.
7-2\sqrt{70}+10
The square of \sqrt{10} is 10.
17-2\sqrt{70}
Add 7 and 10 to get 17.
\left(\sqrt{7}\right)^{2}-2\sqrt{7}\sqrt{10}+\left(\sqrt{10}\right)^{2}
Use binomial theorem \left(a-b\right)^{2}=a^{2}-2ab+b^{2} to expand \left(\sqrt{7}-\sqrt{10}\right)^{2}.
7-2\sqrt{7}\sqrt{10}+\left(\sqrt{10}\right)^{2}
The square of \sqrt{7} is 7.
7-2\sqrt{70}+\left(\sqrt{10}\right)^{2}
To multiply \sqrt{7} and \sqrt{10}, multiply the numbers under the square root.
7-2\sqrt{70}+10
The square of \sqrt{10} is 10.
17-2\sqrt{70}
Add 7 and 10 to get 17.
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