<=> 10+x+11+x+13+x+16+x+...+38+x=892

<=>7x.(10+13+16+20+25+31+38)      =892

<=>7x.153                                           =892

<=>7x                                                  =892:153=\(\frac{892}{153}\)

Vậy x                                                    =\(\frac{892}{153}:7\)=\(\frac{892}{1071}\)

614767560 theo minh do la cau tra loi cho cau hoi cua ban

 cho mình cách giải 

để tính hợp lí

bằng 614 767 560

ta co tu suy nghi 

chuẩn CMNR ;+

Cách 1:

 A = \(\frac{2}{1.2.3}\)+ \(\frac{2}{2.3.4}\)+ \(\frac{2}{3.4.5}\)+ .... + \(\frac{2}{36.37.38}\)+ \(\frac{2}{37.38.39}\)

A = \(\frac{3-1}{1.2.3}\)+ \(\frac{4-2}{2.3.4}\)+ \(\frac{5-3}{3.4.5}\)+ ... + \(\frac{38-36}{36.37.38}\)+ \(\frac{39-37}{37.38.39}\)

A = ( \(\frac{3}{1.2.3}\)- \(\frac{1}{1.2.3}\) )+ ( \(\frac{4}{2.3.4}\)-\(\frac{2}{2.3.4}\)) + ... + (\(\frac{38}{36.37.38}\)- \(\frac{36}{36.37.38}\)) + (\(\frac{39}{37.38.39}\)- \(\frac{37}{37.38.39}\))

A = ( \(\frac{1}{1.2}\)- \(\frac{1}{2.3}\)) + (\(\frac{1}{2.3}\) -\(\frac{1}{3.4}\) ) + ... + ( \(\frac{1}{36.37}\)- \(\frac{1}{37.38}\)) + ( \(\frac{1}{37.38}\)- \(\frac{1}{38.39}\))

A = \(\frac{1}{1.2}\)+ (-\(\frac{1}{2.3}\)+ \(\frac{1}{2.3}\)) + (-\(\frac{1}{3.4}\)+ \(\frac{1}{3.4}\)) + ..... + ( -\(\frac{1}{37.38}\)+\(\frac{1}{37.38}\)) - \(\frac{1}{38.39}\)

A = \(\frac{1}{1.2}\)+ 0 + 0 + 0 +... + 0 - \(\frac{1}{38.39}\)

A = \(\frac{1}{1.2}\)- \(\frac{1}{38.39}\)= \(\frac{741}{1482}\)- \(\frac{1}{1482}\)= \(\frac{740}{1482}\)=\(\frac{370}{741}\)

=>29x+696=928

=>29x=232

hay x=8

x=8 ^-^

=>29x+696=928

=>29x=232

Ta có: \(-\left(38-x\right)-\left(37-x\right)=30-x\)

\(\Leftrightarrow-38+x-37+x-30+x=0\)

\(\Leftrightarrow3x-105=0\)

\(\Leftrightarrow3x=105\)

hay x=35

Vậy: x=35

-(38-x)-(37-x)=30-x

⇔-38+x-37+x=30-x

⇔x+x+x=30+38+37

⇔3x=105

⇔x=105 : 3

⇔x=35

Vậy x=35.

=5,230226175x 10⁴⁴

làm thế nào vậy các bạn ?

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