Toán Lớp 9: Cho A = 1 – $\sqrt{x}$
Tính A với x = 6 – $\sqrt{2 căn 5}$
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Toán Lớp 9: Cho A = 1 – $\sqrt{x}$
Tính A với x = 6 – $\sqrt{2 căn 5}$
Comments ( 2 )
Dkxd:x \ge 0\\
x = 6 – 2\sqrt 5 \left( {tmdk} \right) = {\left( {\sqrt 5 – 1} \right)^2}\\
\Leftrightarrow \sqrt x = \left| {\sqrt 5 – 1} \right| = \sqrt 5 – 1\\
\Leftrightarrow A = 1 – \sqrt x \\
= 1 – \left( {\sqrt 5 – 1} \right)\\
= 1 – \sqrt 5 + 1\\
= 2 – \sqrt 5
\end{array}$