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Bài 2:
a, \(\dfrac{5}{23}\) \(\times\) \(\dfrac{17}{26}\) + \(\dfrac{5}{23}\) \(\times\) \(\dfrac{9}{26}\)
= \(\dfrac{5}{23}\) \(\times\) ( \(\dfrac{17}{26}\) + \(\dfrac{9}{26}\))
= \(\dfrac{5}{23}\) \(\times\) \(\dfrac{26}{26}\)
= \(\dfrac{5}{23}\)
b, \(\dfrac{3}{4}\) \(\times\) \(\dfrac{7}{9}\) + \(\dfrac{7}{4}\) \(\times\) \(\dfrac{3}{9}\)
= \(\dfrac{7}{12}\) + \(\dfrac{7}{12}\)
= \(\dfrac{14}{12}\)
= \(\dfrac{7}{6}\)
a) \(\frac{15}{9}:\frac{3}{4}:\frac{7}{5}=\frac{15}{9}.\frac{4}{3}.\frac{5}{7}=\frac{300}{189}=\frac{100}{63}\)
b ) \(\frac{23}{7}.\frac{25}{2}-\frac{23}{7}.\left(5+\frac{1}{2}\right)=\frac{23}{7}.\left(\frac{25}{2}-\frac{11}{2}\right)=\frac{23}{7}.7=23\)
a) 1+2+3+...+2018
=[(2018-1):1+1].(2018+1):2
=2018.2019:2
=2037171
b) 4+7+10+13+...+2017
=[(2017-4):3+1].(2017+4):2
=672.2021:2
=679056
c) 1+2-3-4+5+6-7-8+9+10-11-12+13+14
=(1+2-3-4)+(5+6-7-8)+(9+10-11-12)+13+14
=-4+(-4)+(-4)+13+14
=-12+27
=15
d) 23 x 75 + 25 x 23 + 180
=23 x (75+25) +180
=23 x 100 +180
=2300+180
2480
chúc ban hoc tốt nha
a) Số số hạng: ( 2018 - 1 ) : 1 + 1 = 2018
Tổng: 2018 x ( 2018 + 1 ) : 2 = 2 037 171
a) \(23\times57+42\times23+23=23\times\left(57+42+1\right)\)
\(=23\times100=2300\)
b) \(\frac{2}{9}\times\frac{5}{7}+\frac{2}{9}\times\frac{2}{7}=\frac{2}{9}\times\left(\frac{5}{7}+\frac{2}{7}\right)\)
\(=\frac{2}{9}\times1=\frac{2}{9}\)
a) 23 x 57 + 42 x 23 + 23
= 23 x ( 57 + 42 + 1 )
= 23 x 100
= 2300
b) \(\frac{2}{9}\times\frac{5}{7}+\frac{2}{9}\times\frac{2}{7}\)
\(=\frac{2}{9}\times\left(\frac{5}{7}+\frac{2}{7}\right)\)
\(=\frac{2}{9}\times1\)
\(=\frac{2}{9}\)
Học tốt #
a) \(23\text{}\times57+42\text{}\times23+23\)
\(=23\text{}\times\left(57+42+1\right)\)
\(=23\text{}\times100\)
\(=2300\)
b) \(\frac{2}{9}\text{}\times\frac{5}{7}+\frac{2}{9\text{}}\text{}\times\frac{2}{7}\)
\(=\frac{2}{9}\text{}\times\left(\frac{5}{7}+\frac{2}{7}\right)\)
\(=\frac{2}{9}\text{}\times1\)
\(=\frac{2}{9}\)
_Chúc bạn học tốt_
a) 23 x 57 +42 x 23 +23 = 23 x 57 +42 x 23 +23 x 1
= 23 x (57 +42 +1) = 23 x 100 = 2300.
b) \(\frac{2}{9}\)x \(\frac{5}{7}\)+ \(\frac{2}{9}\)x \(\frac{2}{7}\)=\(\frac{2}{9}\) x \(\left(\frac{5}{7}+\frac{2}{7}\right)\)
=\(\frac{2}{9}\)x \(\frac{7}{7}\)= \(\frac{2}{9}\)x \(1\)= \(\frac{2}{9}\).
k mik nhé !!
a, \(23\times57+42\times23+23\)\(=23\times\left(57+42+1\right)\)\(=23\times100=2300\)
b, \(\frac{2}{9}\times\frac{5}{7}+\frac{2}{9}\times\frac{2}{7}\)\(=\frac{2}{9}\left(\frac{5}{7}+\frac{2}{7}\right)=\frac{2}{9}\)
a) 23x57+42x23+23
=23x(57+42+1)
=23x100
=2300
b) \(\frac{2}{9}\cdot\frac{5}{7}+\frac{2}{9}\cdot\frac{2}{7}\)
\(=\frac{2}{9}\cdot\left(\frac{5}{7}+\frac{2}{7}\right)\)
\(=\frac{2}{9}\cdot1=\frac{2}{9}\)
= 23 x ( 57 + 42 + 1 )
= 23 x 100
= 2300
= 2 / 9 x ( 5 / 7 + 2 / 7 )
= 2 /9 x 1
= 9 / 2