41+2+4+576
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![](https://rs.olm.vn/images/avt/0.png?1311)
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75 km 641 m = 75.641 km ; 41 cm2 5 mm2 = 41.05 cm2
1 giờ 30 phút = 1.5 giờ ; 8 m3 20 dm3 = 8.02 dm3
4 km 576 m = 4.576 km ; 12 kg 24 g = 0.012024 kg
1 phút 15 giây = 1.25 phút ; 34 cm2 5 mm2 = 34.05 cm2
679 dm3 = 0.679 m3 ; 2 m3 18 dm3 = 2.018 m3
![](https://rs.olm.vn/images/avt/0.png?1311)
\(A=\dfrac{1}{4}+\dfrac{1}{16}+...+\dfrac{1}{576}\)
=1/2^2(1+1/2^2+...+1/12^2)
1/2^2+1/3^2+...+1/12^2<1-1/2+1/2-1/3+...+1/11-1/12=11/12
=>1+1/2^2+1/3^2+...+1/12^2<1+11/12=23/12
=>A<23/12*1/4=23/48<23/46=1/2
![](https://rs.olm.vn/images/avt/0.png?1311)
\(4\left(2x+1\right)^2=576\)
\(\left(2x+1\right)^2=\dfrac{576}{4}=144=12^2\)
\(\Leftrightarrow\left[{}\begin{matrix}2x+1=12\\2x+1=-12\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}2x=11\\2x=-13\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{11}{2}\\x=-\dfrac{13}{2}\end{matrix}\right.\)
\(4\cdot(2x+1)^2=576\\\Rightarrow (2x+1)^2=576:4\\\Rightarrow(2x+1)^2=144\\\Rightarrow(2x+1)^2=(\pm12)^2\)
\(\Rightarrow\left[{}\begin{matrix}2x+1=12\\2x+1=-12\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}2x=11\\2x=-13\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{11}{2}\\x=-\dfrac{13}{2}\end{matrix}\right.\)
Vậy: \(x\in\left\{-\dfrac{13}{2};\dfrac{11}{2}\right\}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(A=\frac{1}{4}+\frac{1}{16}+....+\frac{1}{576}\)
\(\Rightarrow4A=1+\frac{1}{4}+....+\frac{1}{144}\)
\(\Rightarrow4A-A=1-\frac{1}{576}\)
\(\Rightarrow3A=1-\frac{1}{576}\)
\(\Rightarrow A=\frac{1-\frac{1}{576}}{3}\)
Ta có: \(\frac{1-\frac{1}{576}}{3}< \frac{1}{3}< \frac{1}{2}\)
vậy suy ra đpcm
A=14 +116 +....+1576
⇒4A=1+14 +....+1144
⇒4A−A=1−1576
⇒3A=1−1576
⇒A=1−1576 3
Ta có: 1−1576 3 <13 <12
vậy suy ra đpcm
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
63 576 - 96 x 4
=63 576 - 384
=63 192
Nhớ ấn đúng nha!!
đáp án là 623 nha bn
ai tích mk mk tích lại cho!
\(41+2+4+576=623\)