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= 28/15 . 3/4 - ( 11/20 + 1/4 ) : 7/3
= 28/15 . 3/4 - 4/5 : 7/3
= 7/5 - 12/35
= 37/35
= \(\dfrac{28}{15}\) . \(\dfrac{3}{4}\) - (\(\dfrac{11}{20}\) + \(\dfrac{1}{4}\)) : \(\dfrac{7}{3}\)
= \(\dfrac{7}{5}\) - (\(\dfrac{11}{20}\) + \(\dfrac{5}{20}\)) : \(\dfrac{7}{3}\)
= \(\dfrac{7}{5}\) - \(\dfrac{16}{20}\) : \(\dfrac{7}{3}\)
= \(\dfrac{7}{5}\) - \(\dfrac{16}{20}\) x \(\dfrac{3}{7}\)
= \(\dfrac{7}{5}\) - \(\dfrac{12}{35}\)
= \(\dfrac{49}{35}\) - \(\dfrac{12}{35}\)
= \(\dfrac{37}{35}\)
5.\(-\dfrac{3}{7}+\dfrac{5}{13}+\dfrac{-4}{12}=-\dfrac{103}{273}\)
b.\(-\dfrac{5}{21}+\dfrac{-2}{21}+\dfrac{8}{24}=\dfrac{-5-2}{21}+\dfrac{8}{24}=-\dfrac{7}{21}+\dfrac{8}{24}=-\dfrac{1}{3}+\dfrac{8}{24}=0\)
c.\(\dfrac{5}{13}+\dfrac{-5}{7}+\dfrac{-20}{41}+\dfrac{8}{13}+\dfrac{-21}{41}=\left(\dfrac{5}{13}+\dfrac{8}{13}\right)+\left(\dfrac{-20}{41}+\dfrac{-21}{41}\right)+-\dfrac{5}{7}=1-1-\dfrac{5}{7}=-\dfrac{5}{7}\)
= 4/9 : -8 - (-1/4 + 9/20) : 14/5
= 4/9 : -8 - 1/5 : 14/5
= -1/18 - 1/5 : 14/5
= -1/18 - 1/14
= -8/63
\(\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{99.100}\)
\(=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{99}-\frac{1}{100}\)
\(=\frac{1}{2}-\frac{1}{100}\)
\(=\frac{49}{100}\)
Mk ghi hơi ngắn nên mong bn sẽ hiểu.
CHÚC BẠN HỌC TỐT!
Trả lời
\(\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+\frac{1}{4\cdot5}+...+\frac{1}{99\cdot100}\)
\(=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{99}-\frac{1}{100}\)
\(=\frac{1}{2}-\frac{1}{100}\)
\(=\frac{49}{100}\)
Trả lời
33.x+135=26.9
33.x+135=234
33.x =234-135
33.x =99
x =99:33
x =3 nha !
Tk giúp mk nha !
1) -(-17) - |-5|
=17-5
=12
2) - |+12| + (-14)
=-12+(-14)
=-26
3) -(+15) + |-7|
=-15+7
=-8
4) (-9) + -(-13)
=-9+13
=4
5) - (-12) + 0
=12+0
=12
6) - (-15) + (-15)
=15+(-15)
=0
7) -(-27) - (+27)
=27-27
=0
8) - (-13) - |-13|
=13-13
=0
9) - |-13| - |-17|
=-13-17
=-30
10) |-25| + |-17|
=25+17
=42
11) -18 + |-5|
=-18+5
=-13
12) |-20| - (-27)
=20+27
=47
13) - |-32| - (+15)
=-32-15
=-47
14) - (-25) - |-48|
=25-48
=-23
dễ mà
tick mk đi mk giải hết
nhưng ghi kết quả thui nha ^_^
5) 24*(15+49)+12*(50+42)
=24*64+12*92
=24*64+12*2*46
=24*64+24*46
=24*(64+46)
=24*110
=2640
\(1\dfrac{13}{15}\times0,75-\left(\dfrac{8}{15}+25\%\right)\)
\(=\dfrac{28}{15}\times\dfrac{3}{4}-\dfrac{8}{15}-25\%\)
\(=\dfrac{7}{5}-\dfrac{8}{15}-\dfrac{1}{4}\)
\(=\dfrac{13}{15}-\dfrac{1}{4}\)
\(=\dfrac{37}{60}\)
-362/15