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\((\)125-120\()\)x45
5x45=225
\(\dfrac{30x25x7x8}{75x8x12x14}\)=\(\dfrac{10\cdot1\cdot7\cdot1}{1\cdot1\cdot1\cdot12\cdot2}\)=\(\dfrac{70}{24}\)
( 1 + 3 + 5 + 7 +...+ 2019) \(\times\) ( 4848 \(\times\) 75 - 7575 \(\times\) 48):51
=(1 + 3 + 5 + 7 +...+2019)\(\times\)( 48 \(\times\) 101 \(\times\) 75 - 75 \(\times\) 101 \(\times\)48):51
=(1+3+5+7+...+2019) \(\times\) ( 48 \(\times\) 101 \(\times\) 75 - 48 \(\times\) 101 \(\times\) 75):51
=(1+3+5+7...+2019)\(\times\)0 : 51
= 0: 51
= 0
Trên tia õ lấy 2 điểm C,D sao cho OC=6cm , OD=2cm
Gọi M là trung điểm của đạn thẳng CD .Tính độ dài các đoạn thẳng MD,MC,OM
Bài giải
a, \(\frac{4}{5}-\frac{2}{3}+\frac{1}{5}-\frac{1}{3}\)
\(=\left(\frac{4}{5}+\frac{1}{5}\right)-\left(\frac{2}{3}+\frac{1}{3}\right)=1-1=0\)
b, \(\frac{2}{5}\text{ x }\frac{7}{4}-\frac{2}{5}\text{ x }\frac{3}{7}\)
\(=\frac{2}{5}\text{ x }\left(\frac{7}{4}-\frac{3}{7}\right)=\frac{2}{5}\text{ x }\frac{37}{28}=\frac{37}{70}\)
c, \(\frac{13}{4}\text{ x }\frac{2}{3}\text{ x }\frac{4}{13}\text{ x }\frac{3}{12}=\frac{13\text{ x }2\text{ x }4\text{ x }3}{4\text{ x }3\text{ x }13\text{ x }12}=\frac{1}{6}\)
d, \(\frac{75}{100}+\frac{18}{21}+\frac{19}{32}+\frac{1}{4}+\frac{3}{21}+\frac{13}{32}\)
\(=\frac{3}{4}+\frac{18}{21}+\frac{19}{32}+\frac{1}{4}+\frac{3}{21}+\frac{13}{32}\)
\(=\left(\frac{3}{4}+\frac{1}{4}\right)+\left(\frac{18}{21}+\frac{3}{21}\right)+\left(\frac{19}{32}+\frac{13}{32}\right)\)
\(=1+1+1\)
\(=3\)
e, \(\frac{2}{5}+\frac{6}{9}+\frac{3}{4}+\frac{3}{5}+\frac{1}{3}+\frac{1}{4}\)
\(=\frac{2}{5}+\frac{2}{3}+\frac{3}{4}+\frac{3}{5}+\frac{1}{3}+\frac{1}{4}\)
\(=\frac{1}{5}\left(2+3\right)+\frac{1}{3}\left(2+1\right)+\frac{1}{4}\left(3+1\right)\)
\(=\frac{1}{5}\cdot5+\frac{1}{3}\cdot3+\frac{1}{4}\cdot4\)
\(=1+1+1\)
\(=3\)
a, \(\frac{4}{5}-\frac{2}{3}+\frac{1}{5}-\frac{1}{3}\)
\(=\left(\frac{4}{5}+\frac{1}{5}\right)-\left(\frac{2}{3}+\frac{1}{3}\right)=1-1=0\)
b, \(\frac{2}{5}\text{ x }\frac{7}{4}-\frac{2}{5}\text{ x }\frac{3}{7}\)
\(=\frac{2}{5}\text{ x }\left(\frac{7}{4}-\frac{3}{7}\right)=\frac{2}{5}\text{ x }\frac{37}{28}=\frac{37}{70}\)
c, \(\frac{13}{4}\text{ x }\frac{2}{3}\text{ x }\frac{4}{13}\text{ x }\frac{3}{12}=\frac{13\text{ x }2\text{ x }4\text{ x }3}{4\text{ x }3\text{ x }13\text{ x }12}=\frac{1}{6}\)
d, \(\frac{75}{100}+\frac{18}{21}+\frac{19}{32}+\frac{1}{4}+\frac{3}{21}+\frac{13}{32}\)
\(=\frac{3}{4}+\frac{18}{21}+\frac{19}{32}+\frac{1}{4}+\frac{3}{21}+\frac{13}{32}\)
\(=\left(\frac{3}{4}+\frac{1}{4}\right)+\left(\frac{18}{21}+\frac{3}{21}\right)+\left(\frac{19}{32}+\frac{13}{32}\right)\)
\(=1+1+1\)
\(=3\)
e, \(\frac{2}{5}+\frac{6}{9}+\frac{3}{4}+\frac{3}{5}+\frac{1}{3}+\frac{1}{4}\)
\(=\frac{2}{5}+\frac{2}{3}+\frac{3}{4}+\frac{3}{5}+\frac{1}{3}+\frac{1}{4}\)
\(=\frac{1}{5}\left(2+3\right)+\frac{1}{3}\left(2+1\right)+\frac{1}{4}\left(3+1\right)\)
\(=\frac{1}{5}\cdot5+\frac{1}{3}\cdot3+\frac{1}{4}\cdot4\)
\(=1+1+1\)
\(=3\)
1 a) x: 2+4 = 240
x: 2 = 240 - 4
x = 236 x 2
x = 472
b) 14: x + 6 = 8
14 : x = 8 - 6
x = 14 : 2
x = 7
c)X: \(\frac{1}{4}\)x 5 = 50
x: \(\frac{1}{4}\) = 50 : 5
x = 10 x \(\frac{1}{4}\)
x = \(\frac{10}{4}\)
d) x : \(\frac{7}{3}\)+ 4 =16
x : \(\frac{7}{3}\) = 16 - 4
x = 12 x \(\frac{7}{3}\)
x = 28
2a) 2 x 4 x 6
= 8 x 6
= 48
b) 75 x 4 + 75 x 98 - 75 x 2
= 75 x (4+98-2)
= 75 x 100
= 7500
c) 5 x 2 x 4 x 6
= (5 x 2)x(4 x 6)
= 10 x 24
= 240
\(\dfrac{8\times3\times4}{16\times3}=\dfrac{8\times3\times2\times2}{2\times8\times3}=2.\\ \dfrac{30\times25\times7\times8}{75\times8\times12\times14}=\dfrac{5\times2\times3\times5\times5\times7\times8}{3\times5\times5\times8\times2\times2\times3\times2\times7}=\dfrac{5}{12}.\)
x + ( x + 5 ) x 3 = 75
x + 3x + 15 = 75
4x = 60
x = 15
\(x+\left(x+5\right)\cdot3=75\)
\(x+3x+15=75\)
\(x+3x=75-15\)
\(4x=60\)
\(x=60:4\)
\(x=15\)