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\(\frac{4678\times4679+4680\times31+4648}{4680\times4679-4678\times4679}\)
\(\Leftrightarrow\frac{4679\times4678+4679\times31+4679}{4679\times\left(4680-4678\right)}\)
\(=\frac{4679\times\left(4678+31+1\right)}{4679\times2}\)
\(=\frac{4679\times4710}{4679\times2}\)
\(=\frac{4710}{2}\)
\(=2355\)
\(\frac{4678\cdot4679+4680\cdot31+4648}{4680\cdot4679-4678.4679}\)=\(\frac{4678\cdot4679+\left(4680-1\right)\cdot31+4648+31}{4680\cdot4679-4678.4679}\)
=\(\frac{4678\cdot4679+4679\cdot31+4679}{4680\cdot4679-4678.4679}\)=\(\frac{\left(4678+31+1\right)\cdot4679}{\left(4680-4678\right).4679}\)=\(\frac{4710}{2}\)=2355
a) 1,28:0,125+1,28×0,25+1,28×1,75
=1,28x(8+0,25+1,75)
=1,28x10=12,8
b) bạn nên viết rõ ra
\(=\dfrac{4678^2+4678+4678\cdot31+2\cdot31+4648}{4678^2+3\cdot4678+2-4678^2-4678}\)
\(=\dfrac{4678^2+4678\cdot32+4678+32}{2\cdot4678+2}=\dfrac{4678\left(1+4678\right)+32\cdot4679}{2\left(4678+1\right)}\)
\(=\dfrac{4678+32}{2}=2355\)
4678×4679+4680×314648=1494441002
4680×4679-4678×4679=9358
\(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}=\frac{32}{64}+\frac{16}{64}+\frac{8}{64}+\frac{4}{64}+\frac{2}{32}+\frac{1}{64}\)
\(\frac{32+16+8+4+2}{64}=\frac{62}{64}=\frac{31}{32}\)
Tk mh nhé , mơn nhìu !!!
~ HOK TỐT ~
\(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}\)\(+\frac{1}{64}\)
= 32/64 + 16/64 + 8/64 + 4/64 + 2/64 + 1/64
= 63/64
Đặt \(A=\frac{7}{1\cdot5}+\frac{7}{5\cdot9}+\frac{7}{9\cdot13}+\frac{7}{13\cdot17}+\frac{7}{17\cdot21}\)
\(\frac{4}{7}A=\frac{4}{7}\left(\frac{7}{1\cdot5}+\frac{7}{5\cdot9}+\frac{7}{9\cdot13}+\frac{7}{13\cdot17}+\frac{7}{17\cdot21}\right)\)
\(\frac{4}{7}A=\frac{4}{1\cdot5}+\frac{4}{5\cdot9}+\frac{4}{9\cdot13}+\frac{4}{13\cdot17}+\frac{4}{17\cdot21}\)
\(\frac{4}{7}A=1-\frac{1}{5}+\frac{1}{5}-\frac{1}{9}+\frac{1}{9}-\frac{1}{13}+\frac{1}{13}-\frac{1}{17}+\frac{1}{17}-\frac{1}{21}\)
\(\frac{4}{7}A=1-\frac{1}{21}\)
\(\frac{4}{7}A=\frac{20}{21}\)
\(A=\frac{20}{21}:\frac{4}{7}=\frac{20}{21}\cdot\frac{7}{4}=\frac{5}{3}\)
Đặt biểu thức trên là A
\(\frac{4xA}{7}=\frac{4}{1x5}+\frac{4}{5x9}+\frac{4}{9x13}+\frac{4}{13x17}+\frac{4}{17x21}\)
\(\frac{4xA}{7}=\frac{5-1}{1x5}+\frac{9-5}{5x9}+\frac{13-9}{9x13}+\frac{17-13}{13x17}+\frac{21-17}{17x21}\)
\(\frac{4xA}{7}=1-\frac{1}{5}+\frac{1}{5}-\frac{1}{9}+\frac{1}{9}-\frac{1}{13}+\frac{1}{13}-\frac{1}{17}+\frac{1}{17}-\frac{1}{21}\)
\(\frac{4xA}{7}=1-\frac{1}{21}=\frac{20}{21}\Rightarrow A=\frac{20}{21}.\frac{7}{4}=\frac{5}{3}\)
-Bạn eii :) K cho p / s tính đc ạ ?
Viết đề đi bn eii :D Đề thiếu kìa :)
#Bổ sung đề đi
\(\frac{4678.4679+4680.31+4648}{4680.4679-4687.4679}\)
\(=\frac{4678.4679+4679.31+(31+4648)}{4679.\left(4680-4687\right)}\)
\(=\frac{4678.4679+4679.31+4679}{4679.\left(-7\right)}\)
\(=\frac{4679.\left(4678+31+1\right)}{4679.\left(-7\right)}\)
\(=\frac{4679.4710}{4679.\left(-7\right)}=\frac{4710}{-7}=\frac{-4710}{7}\)
lp 5 chưa hok đến số âm, nhưng bài này lại ra kp âm! nên b xem lại đề giúp mk nha!