Evaluate
105-20\sqrt{7}\approx 52.084973779
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-20\sqrt{7}+15\left(\sqrt{7}\right)^{2}
Use the distributive property to multiply 5\sqrt{7} by -4+3\sqrt{7}.
-20\sqrt{7}+15\times 7
The square of \sqrt{7} is 7.
-20\sqrt{7}+105
Multiply 15 and 7 to get 105.
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