IR IRAN(Islamic Republic of Iran)
Giới thiệu về bản thân
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2023-09-10 14:26:43
2022-07-24 17:07:50
ĐKXĐ : \(x\ge-4\)
(2x + 1)2 = (x + 4)\(\sqrt{4x^2+1}\)
<=> \(4x^2+1+4x=x\sqrt{4x^2+1}+4\sqrt{4x^2+1}\)
<=> \(\left(\sqrt{4x^2+1}-4\right)\left(\sqrt{4x^2+1}-x\right)=0\)
<=> \(\left[{}\begin{matrix}\sqrt{4x^2+1}=4\\\sqrt{4x^2+1}=x\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}4x^2=15\\\left\{{}\begin{matrix}3x^2+1=0\\x\ge0\end{matrix}\right.\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\pm\dfrac{\sqrt{15}}{2}\left(tm\right)\\∄x\end{matrix}\right.\Leftrightarrow x=\pm\dfrac{\sqrt{15}}{2}\)
2022-07-08 11:09:07
B = (sin2a + cos2a)2 = 12 = 1
2022-07-06 09:09:02
Đặt x25 = t
=> x100 + x50 + 1 = t4 + t2 + 1
= t4 + 2t2 + 1 - t2
= (t2 + 1)2 - t2
= (t2 - t + 1)(t2 + t + 1)
= (x50 - x25 + 1)(x50 + x25 + 1)
