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Question

bài 1: tính nhanh:

$\frac{18.123+9.436.2+3.5310+6}{1+4+7+...+100-410}$

Đức Minh · Accepted Answer

$\frac{18\cdot123+9\cdot436+2\cdot5310+6}{1+4+7+...+100-410}$

$=\frac{18\cdot123+18\cdot436+18\cdot885+6}{\frac{\left(\frac{\left(100-1\right)}{3}+1\right)}{2}\cdot\left(100+1\right)-410}$

$=\frac{18\cdot\left(123+436+885\right)+6}{1717-410}$

$=\frac{18\cdot1444+6}{1307}$

$=19,89$Câu trả lời: $\frac{18\cdot123+9\cdot436+2\cdot5310+6}{1+4+7+...+100-410}$

$=\frac{18\cdot123+18\cdot436+18\cdot885+6}{\frac{\left(\frac{\left(100-1\right)}{3}+1\right)}{2}\cdot\left(100+1\right)-410}$

$=\frac{18\cdot\left(123+436+885\right)+6}{1717-410}$

$=\frac{18\cdot1444+6}{1307}$

$=19,89$