Toan kho

P

popstar1102



tìm a+b biết $\sqrt{14-6\sqrt{5}}=a+b\sqrt{5}$

ta có $\sqrt{14-6\sqrt{5}}=\sqrt{5-2.3\sqrt{5}+3^2}$

=$\sqrt{(9-\sqrt{5})^2}=9-\sqrt{5}$
\Rightarrow a=9 b=-1
a+b=8
 
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