(18.123+9.436.2+3.5310.6)/(1+4+7+.....+100-410)
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Ta có:
+) \(1+4+7+...+100=\left(1+100\right)+\left(4+97\right)+...+\left(49+52\right)\)(34 cặp)
\(=101.34=3434\)
+) \(3434-410=3024\)
+) \(\left(18.123+9.436.2+3.5310.6\right)=18\left(123+436+5310\right)\)
\(=18.5869=105642\)
Vậy \(A=105642:3024\approx34,93\)
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\(\left(18\cdot123+9\cdot436.2+3\cdot5310\cdot6\right):\left(1+4+7+.....+100\right)-410\)
\(=\left(18\cdot123+18\cdot436+18\cdot5310\right):1717-410\)
\(=18\cdot\left(123+436+5310\right):1717-410\)
\(=18\cdot5869:1717-410\)
\(=61,52-410\)
\(=-348,47\)
đề bài sai hay sao đó bạn
kiểm tra lại đi
![](https://rs.olm.vn/images/avt/0.png?1311)
Phân tích: \(\left(18.123+9.436.2-3.3510.6\right)=18.123+18.436-18.5310\)\(\Leftrightarrow18.\left(123+436-3510\right)\)( chung số 18 )
\(\Leftrightarrow18.\left(-4751\right)=-85518\)
Tiếp tục phân tích vế sau:
\(\left(1+4+7+...+100-410\right)=\dfrac{\left[\left(100-1\right):3+1\right].\left(100+1\right)}{2}-410\)\(\Leftrightarrow1717-410=1307\)
\(\Leftrightarrow-85518:1717=\dfrac{-85518}{1717}\)
Vậy.............................
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