256. "Be patient," she said to him
.→ She told him ………………………………………
257. "Go to your room," her father said to her
.→ Her father told her ………………………………………
258. "Hurry up," she said to us.
→ She told us ………………………………………
259. "Give me the key," he told her
.→ He asked her ………………………………………
260. "Play it again, Sam," she said.
→ She asked Sam ………………………………………
261. "Sit down, Caron" he said
→ He asked Caron ………………………………………
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\(A=256-\dfrac{256}{2}-\dfrac{256}{2^2}-\dfrac{256}{2^3}-.......-\dfrac{256}{2^9}\)
\(\Leftrightarrow A=256\left(1-\dfrac{1}{2}-\dfrac{1}{2^2}-\dfrac{1}{2^3}-.....-\dfrac{1}{2^9}\right)\)
Đặt \(B=\dfrac{1}{2}-\dfrac{1}{2^2}-\dfrac{1}{2^3}-.....-\dfrac{1}{2^9}\)
\(\Leftrightarrow2B=1-\dfrac{1}{2}-\dfrac{1}{2^2}-.....-\dfrac{1}{2^8}\)
\(\Leftrightarrow2B-B=1-\dfrac{1}{2^9}\)
\(\Leftrightarrow B=1-\dfrac{1}{2^9}\)
\(\Leftrightarrow A=256\left(1-\dfrac{1}{2^9}\right)\)
\(\Leftrightarrow A=256-\dfrac{1}{2^9}\)
\(\Leftrightarrow A=2^8-\dfrac{1}{2^9}\)
\(\Leftrightarrow A=\dfrac{2^{17}}{2^9}-\dfrac{1}{2^9}\)
\(\Leftrightarrow A=\dfrac{2^{17}-1}{2^9}\)
Vậy \(\Leftrightarrow A=\dfrac{2^{17}-1}{2^9}\)
Chúc bạn học tốt >w<
\(=\dfrac{64^2+256^2}{256^2+1024^2}=\dfrac{64^2\left(1+4^2\right)}{256^2\left(1+4^2\right)}=\left(\dfrac{64}{256}\right)^2=\dfrac{1}{16}\)
2x - ( -7) = 256-1146
2x -(-7) = -890
2x =-897
x = -897 : 2 = -448.5
=> 2x + 7 = 256 - 256 - 89
=> 2x + 7 = -89
=> 2x = -96
=> x = -48
256. "Be patient," she said to him
.→ She told him ……to be patient…………………………………
257. "Go to your room," her father said to her
.→ Her father told her ……to go to her room…………………………………
258. "Hurry up," she said to us.
→ She told us ……to hurry up…………………………………
259. "Give me the key," he told her
.→ He asked her ……to give him the key…………………………………
260. "Play it again, Sam," she said.
→ She asked Sam …to play it again……………………………………
261. "Sit down, Caron" he said
→ He asked Caron …to sit down……………………………………