K
Khách
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KH
28 tháng 2 2018
a) \(x=\dfrac{1}{4}+\dfrac{2}{13}\)
\(x=\dfrac{13}{52}+\dfrac{8}{52}\)
⇒ \(x=\dfrac{21}{52}\)
b) \(\dfrac{x}{3}=\dfrac{2}{3}+\dfrac{-1}{7}\)
\(\dfrac{x}{3}=\dfrac{14}{21}+\dfrac{-3}{21}\)
\(\dfrac{x}{3}=\dfrac{11}{21}\)
⇒ \(x=\dfrac{11.3}{21}=\dfrac{33}{21}\)
⇒ \(x=\dfrac{11}{7}\)
c) \(\dfrac{-8}{3}+\dfrac{1}{3}< x< \dfrac{-2}{7}+\dfrac{-5}{7}\)
\(\dfrac{-17}{7}< x< -1\)
⇒ \(-17< x< -7\)
⇒ \(x\in\left\{-16;-15,....;-6\right\}\)
d) \(\dfrac{1}{6}+\dfrac{2}{5}\)
\(=\dfrac{5}{30}+\dfrac{12}{30}\)
\(=\dfrac{17}{30}\)
e) \(\dfrac{3}{5}+\dfrac{-7}{4}\)
\(=\dfrac{12}{20}+\dfrac{-35}{20}\)
\(=\dfrac{-23}{20}\)
f) \(\dfrac{4}{13}+\dfrac{-12}{30}\)
\(=\dfrac{4}{13}+\dfrac{-2}{5}\)
\(=\dfrac{20}{65}+\dfrac{-26}{65}\)
\(=\dfrac{-6}{65}\)
g) \(\dfrac{-3}{29}+\dfrac{16}{58}\)
\(=\dfrac{-6}{58}+\dfrac{16}{58}\)
\(=\dfrac{10}{58}\)
h) \(\dfrac{8}{40}+\dfrac{-36}{45}\)
\(=\dfrac{1}{5}+\dfrac{-4}{5}\)
\(=\dfrac{-3}{5}\)
j) \(\dfrac{-8}{18}+\dfrac{15}{27}\)
\(=\dfrac{-2}{9}+\dfrac{5}{9}\)
\(=\dfrac{3}{9}\)
\(=\dfrac{1}{3}\)
NB
0
1 tháng 7 2017
a)15/16:3/8x3/4
=15/16:6/16x12/16
=15/16x16/6x12/16
=15/6x12/16
=30/16=15/8
1 tháng 7 2017
b)5/11x18/29-5/11x8/29+5/11x19/29
=5/11x(18/29-8/29+19/29)
=5/11x1=5/11
QA
5 tháng 3 2020
\(-8.4+19=-32+19=-13\)
\(-11.3-28=-33-28=-61\)
\(4.\left(-15\right)-18=-60-18=-78\)
\(19-4.\left(-12\right)=19+48=67\)
\(-25.\left(-3\right)-54=75-54=21\)
\(-16-7.\left(-4\right)+24\div\left(-8\right)=-16+28-3=9\)
\(15\div\left(-3\right)+30-7.\left(-3\right)=-5+30+21=46\)
\(-48\div\left(-4\right)+15.\left(-5\right)=12-75=-63\)
\(-29+65\div\left(-5\right)+23=-29-13+23=-19\)
\(15\div\left(-5\right)-17-12.\left(-5\right)=-3-17+60=40\)
\(28.\left(-4\right)-17=-112-17=-129\)
\(-19-7.4=-19-28=-47\)
\(-14.\left(-2\right)-16=28-16=12\)
\(13.\left(-3\right)-65-4.\left(-6\right)=-39-65+24=-80\)
\(-24-8.\left(-6\right)+28=-24+48+28=52\)
Chúc bạn hok tốt!!! tỷ tỷ
24 tháng 7 2018
\(\left(\frac{17}{28}+\frac{18}{29}-\frac{19}{30}-\frac{30}{31}\right)\times\left(\frac{-5}{12}+\frac{1}{4}+\frac{1}{6}\right)\)
\(=\left(\frac{17}{28}+\frac{18}{29}-\frac{19}{30}-\frac{30}{31}\right)\times\left(\frac{-5}{12}+\frac{3}{12}+\frac{2}{12}\right)\)
\(=\left(\frac{17}{28}+\frac{18}{29}-\frac{19}{30}-\frac{30}{31}\right)\times\left(\frac{-5+3+2}{12}\right)\)
\(=\left(\frac{17}{28}+\frac{18}{29}-\frac{19}{30}-\frac{30}{31}\right)\times0\)
\(=0\)
_Chúc bạn học tốt_
24 tháng 7 2018
\(\left(\frac{17}{28}+\frac{18}{29}-\frac{19}{30}-\frac{30}{31}\right)\times\left(\frac{-5}{12}+\frac{1}{4}+\frac{1}{6}\right)\)
\(=\left(\frac{17}{28}+\frac{18}{29}-\frac{19}{30}-\frac{30}{31}\right)\times\left(\frac{-5}{12}+\frac{3}{12}+\frac{2}{12}\right)\)
\(=\left(\frac{17}{28}+\frac{18}{29}-\frac{19}{30}-\frac{30}{31}\right)\times\left(\frac{-5+3+2}{12}\right)\)
\(=\left(\frac{17}{28}+\frac{18}{29}-\frac{19}{30}-\frac{30}{31}\right)\times0\)
\(=0\)
_Chúc bạn học tốt_
4 tháng 10 2018
1 + 2-3-4+5+6-7-8+9+...+28-29-30+31 + 32
= 1 + (2-3-4+5) + (6-7-8+9) + ...+(28-29-30+31) + 32
= 1 + 0+0+...+0+32
= 1+32
=33
4 tháng 10 2018
1+2-3-4+5+6-7-8+9+...+28-29-30+31+32?
( 1 + 2 - 3 - 4 ) + ( 5 + 6 - 7 - 8 ) + ...... + ( 29 + 30 - 31 - 32 )
= 0 + 0 + ....+ 0
= 0
\(\left[5^{30}+4.\left(12-7\right)^{30}\right]:5^{29}\)
\(=\left(5^{30}+4.5^{30}\right):5^{29}\)
\(=5^{30}\left(1+4\right):5^{29}\)
\(=5^{30}.5:5^{29}\)
\(=5^{31}:5^{29}\)
\(=5^2\)