Rút gọn:
a, \(\frac{-28}{72}\) b, \(\frac{-75}{-105}\) c, \(\frac{3.5.11.13}{33.35.37}\) d, \(\frac{85-17+34}{51-102}\)
rut gon phan so:
a. 3.5.11.13
33.35.37
b. 85-17+34
51-102
a. 3.5.11.13 3..5.11.13 13 13
33.35.37 = 3.11.5.7.37 = 7.37 = 259
Rút gọn các phân số sau:
a) \(\frac{2.7.13}{26.35}\) b) \(\frac{23.5-23}{4-27}\) c) \(\frac{2130-15}{3550-25}\)
d, \(\frac{1717-101}{2828+404}\) e) \(\frac{3.5.11.13}{33.35.27}\) f) \(\frac{85-17+34}{51-102}\)
a) \(\frac{2.7.13}{26.35}=\frac{2.7.13}{2.13.5.7}=\frac{1}{5}\)
b) \(\frac{23.5-23}{4-27}=\frac{23.\left(5-1\right)}{-23}=\frac{23.4}{-23}=\frac{23.\left(-4\right)}{23}=-4\)
c) \(\frac{2130-15}{3550-25}=\frac{142.15-15}{142.25-25}=\frac{15.\left(142-1\right)}{25.\left(142-1\right)}=\frac{15.141}{25.141}=\frac{15}{25}=\frac{3.5}{5.5}=\frac{3}{5}\)
d) \(\frac{1717-101}{2828+404}=\frac{17.101-101}{28.101+101.4}=\frac{101.\left(17-1\right)}{101.\left(28+4\right)}=\frac{101.16}{101.32}=\frac{16}{32}=\frac{4.4}{2.4.4}=\frac{1}{2}\)
e) \(\frac{3.5.11.13}{33.35.27}=\frac{3.5.11.13}{3.11.5.7.3^3}=\frac{13}{7.3^3}=\frac{13}{189}\)
f) \(\frac{85-17+34}{51-102}=\frac{5.17-17+2.17}{3.17-6.17}=\frac{17.\left(5-1+2\right)}{17.\left(3-6\right)}=\frac{17.6}{17.\left(-3\right)}=\frac{6}{-3}=-2\)
Rút gọn:
a.\(\frac{2.7.13}{26.35}\)
b.\(\frac{3.5.11.13}{33.35.37}\)
c.\(\frac{23.5-23}{4-27}\)
d.\(\frac{1717-101}{2828+404}\)
a) \(\frac{2.7.13}{26.35}=\frac{2.7.13}{2.13.7.5}=\frac{1}{5}\)
b) \(\frac{3.5.11.13}{33.35.37}=\frac{3.5.11.13}{3.11.7.5.37}=\frac{13}{259}\)
c) \(\frac{23.5-23}{4-27}=\frac{23.\left(5-1\right)}{-23}=\frac{4}{-1}=-4\)
d) \(\frac{1717-101}{2828+404}=\frac{101.17-101}{404.7+404}=\frac{101.\left(17-1\right)}{404.\left(7+1\right)}=\frac{101.16}{404.8}=\frac{101.2.8}{101.4.8}=\frac{1}{2}\)
Bà 18 : Thực hiện các phép tính sau = cách hợp lý nhất :
a) ( -40/51 . 0,32 . 17/20 ) : 64/75
b) -10/11 . 8/9 + 7/18 . 10/11
c) 3/14 : 1/28 - 13/21 : 1/28 + 29/42 : 1/28 - 8
d) \(-1\frac{5}{7}.15+\frac{2}{7}.\left(-15\right)+\left(-105\right).\left(\frac{2}{3}-\frac{4}{5}+\frac{1}{7}\right)\)
1, TÍNH : \(\frac{85-17+34}{51-102}\) .
Help me !!!
\(\frac{85-17+34}{51-102}=\frac{102}{-51}=-2\)
Ta thấy:
\(\frac{85-17+34}{51-102}=\frac{17\cdot5-17+17\cdot2}{17\cdot3-17\cdot6}=\frac{17\cdot\left(5-1+2\right)}{17\cdot\left(3-6\right)}=\frac{17\cdot\left(4+2\right)}{17\cdot\left[3+\left(-6\right)\right]}=\frac{17\cdot6}{17\cdot-3}=-2\)
Tính bằng cách hợp lý:
Tính B=\(\frac{48+\frac{34}{31}-\frac{34}{33}+\frac{34}{35}}{72+\frac{51}{31}-\frac{51}{33}+\frac{51}{35}}:\frac{-242423}{363636}\)
a) \(\left(-\frac{40}{51}\cdot0,32\cdot\frac{17}{20}\right):\frac{64}{75}\)
b) \(-\frac{10}{11}\cdot\frac{8}{9}+\frac{7}{18}\cdot\frac{10}{11}\)
c) \(\frac{3}{14}:\frac{1}{28}-\frac{13}{21}:\frac{11}{28}+\frac{29}{42}:\frac{1}{28}-8\)
a ) \(\left(-\frac{40}{51}.0,32.\frac{17}{20}\right):\frac{64}{75}\)
\(=\left(-\frac{40}{51}.\frac{8}{25}.\frac{17}{20}\right):\frac{64}{75}\)
\(=\left(\frac{-40.8.17}{51.25.20}\right):\frac{64}{75}\)
\(=\left(\frac{-16}{75}\right).\frac{75}{64}\)
\(=\frac{-1}{1}.\frac{1}{4}=-\frac{1}{4}\)
B1 tìm x,y,z
a) \(\frac{-3}{6}\)=\(\frac{x}{-2}\)=\(\frac{-18}{y}\)=\(\frac{-z}{24}\)
B2 Lập các cặp p/số bằng nhau từ đẳng thức sau
a) 2.24=6.8
b) (-3).(-12)=4.9
B3 rút gọn
a)\(\frac{2.7.13}{26.35}\)
b)\(\frac{23.5-23}{4.27}\)
c)\(\frac{85-17+34}{51-102}\)
MN GIÚP MIK NHA
\(-\frac{3}{6}=\frac{x}{-2}=-\frac{18}{y}=-\frac{z}{24}\)
Ta có :+) \(-\frac{3}{6}=\frac{x}{-2}\)
\(\Rightarrow x=\frac{\left(-3\right)\left(-2\right)}{6}\)
\(\Rightarrow x=1\)
+)\(-\frac{3}{6}=-\frac{18}{y}\)
\(\Rightarrow y=\frac{6.\left(-18\right)}{-3}\)
\(\Rightarrow y=36\)
+)\(-\frac{3}{6}=-\frac{z}{24}\)
\(\Rightarrow-z=\frac{\left(-3\right)24}{6}\)
\(\Rightarrow-z=-12\)
\(\Rightarrow z=12\)
Vậy........................
Tính
a, A=\(\left(\frac{-40}{51}.0,32.\frac{17}{20}\right).\frac{64}{75}\)
b, B=\(4\frac{5}{9}:\left(\frac{-5}{7}\right)-5\frac{4}{9}:\frac{5}{7}\)
c, C= \(1\frac{5}{7}.15+\frac{2}{9}.\left(-15\right)+105.\left(\frac{-2}{3}+\frac{4}{5}-\frac{1}{7}\right)\)