Question

Tính nhanh:(18.123+9.436.2+3.5310.6):(1+4+7+...+100-410)

Ai giúp mình với!!!!

Answer 1

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.............................