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ó ai giúp mk ko , ai giúp mk nhanh và đúng mk sẽ k cho người đó nhé , ( nhanh chứ ko mk đâng cần)
1.
a, \(\left(15+37\right)+\left(52-37-17\right)\)
\(=15+37+52-37-17\)
\(=50\)
b, \(\left(38-42+14\right)-\left(25-27-15\right)\)
\(=38-42+14-25+27+15\)
\(=27\)
c, \(-\left(21-32\right)-\left(-12+32\right)\)
\(=-21+32+12-32\)
\(=-9\)
d, \(-\left(12+21-23\right)-\left(-23-21+10\right)\)
\(=-12-21+23+23+21-10\)
\(=24\)
e, \(\left(57-725\right)-\left(605-53\right)\)
\(=57-725-605+53\)
\(=-1220\)
f, \(\left(55+45+15\right)-\left(15-55+45\right)\)
\(=55+45+15-15+55-45\)
\(=110\)
2.
c, \(25\left(-47\right)\left(-4\right)\)
\(=-100\left(-47\right)=4700\)
d, \(8\left(125-30000\right)\)
\(=8.125-8.30000\)
\(=1000.240000\)
\(=240000000\)
e, \(512\left(2-128\right)-128\left(-512\right)\)
\(=512\left(2-128\right)+128.512\)
\(=512\left(2-128+128\right)\)
\(=1024\)
3.
4 B(-5) trog đó cs cả số âm là: 10; -20; 35; -40
tất cả các Ư(15) là: \(\pm1;\pm3;\pm5;\pm15\)
LƯU Ý: đề hơi dài, cs sai sót j mong e bỏ qua mà k cho cj nha
a: \(=\dfrac{5}{6}\cdot\dfrac{-12}{7}=\dfrac{-10}{7}\)
b: \(=\dfrac{7}{8}\cdot\dfrac{8}{14}=\dfrac{7}{14}=\dfrac{1}{2}\)
c: \(=\dfrac{4}{5}\cdot\dfrac{-15}{8}=\dfrac{-3}{2}\)
d: \(=\dfrac{15}{16}\cdot\dfrac{8}{25}=\dfrac{15}{25}\cdot\dfrac{1}{2}=\dfrac{3}{5}\cdot\dfrac{1}{2}=\dfrac{3}{10}\)
đ: \(=\dfrac{2}{3}-\dfrac{70}{175}=\dfrac{2}{3}-\dfrac{2}{5}=\dfrac{10-6}{15}=\dfrac{4}{15}\)
Bài 1:
a; \(\dfrac{5}{18}\) + \(\dfrac{8}{19}\) - \(\dfrac{7}{21}\) + (- \(\dfrac{10}{36}\) + \(\dfrac{11}{19}\) + \(\dfrac{1}{3}\)) - \(\dfrac{5}{8}\)
= \(\dfrac{5}{18}\) + \(\dfrac{8}{19}\) - \(\dfrac{1}{3}\) -\(\dfrac{10}{36}\) + \(\dfrac{11}{19}\) + \(\dfrac{1}{3}\) - \(\dfrac{5}{8}\)
= (\(\dfrac{5}{18}\) - \(\dfrac{10}{36}\)) + (\(\dfrac{8}{19}\) + \(\dfrac{11}{19}\)) - (\(\dfrac{1}{3}\) - \(\dfrac{1}{3}\)) - \(\dfrac{5}{8}\)
= (\(\dfrac{5}{18}\) - \(\dfrac{5}{18}\)) + \(\dfrac{19}{19}\) - 0 - \(\dfrac{5}{8}\)
= 0 + 1 - \(\dfrac{5}{8}\)
= \(\dfrac{3}{8}\)
b; \(\dfrac{1}{13}\) + (\(\dfrac{-5}{18}\) - \(\dfrac{1}{13}\) + \(\dfrac{12}{17}\)) - (\(\dfrac{12}{17}\) - \(\dfrac{5}{18}\) + \(\dfrac{7}{5}\))
= \(\dfrac{1}{13}\) - \(\dfrac{5}{18}\) - \(\dfrac{1}{13}\) + \(\dfrac{12}{17}\) - \(\dfrac{12}{17}\) + \(\dfrac{5}{18}\) - \(\dfrac{7}{5}\)
= (\(\dfrac{1}{13}\) - \(\dfrac{1}{13}\)) + (\(\dfrac{12}{17}\) - \(\dfrac{12}{17}\)) + (-\(\dfrac{5}{18}\) + \(\dfrac{5}{18}\)) - \(\dfrac{7}{5}\)
= 0 + 0 + 0 - \(\dfrac{7}{5}\)
= - \(\dfrac{7}{5}\)
Bài 1 c;
\(\dfrac{15}{14}\) - (\(\dfrac{17}{23}\) - \(\dfrac{80}{87}\) + \(\dfrac{5}{4}\)) + (\(\dfrac{17}{23}\) - \(\dfrac{15}{14}\) + \(\dfrac{1}{4}\))
= \(\dfrac{15}{14}\) - \(\dfrac{17}{23}\) + \(\dfrac{80}{87}\) - \(\dfrac{5}{4}\) + \(\dfrac{17}{23}\) - \(\dfrac{15}{14}\) + \(\dfrac{1}{4}\)
= (\(\dfrac{15}{14}-\dfrac{15}{14}\)) + (\(-\dfrac{17}{23}+\dfrac{17}{23}\)) - (\(\dfrac{5}{4}\) - \(\dfrac{1}{4}\)) + \(\dfrac{80}{87}\)
= 0 + 0 - 1 + \(\dfrac{80}{87}\)
= - \(\dfrac{7}{87}\)
a) \(\dfrac{7}{-25}+\dfrac{8}{25}=\dfrac{-7}{25}+\dfrac{8}{25}=\dfrac{1}{25}\)
\(\dfrac{4}{5}+\dfrac{4}{-18}=\dfrac{4}{5+\left(-18\right)}=\dfrac{4}{-13}=\dfrac{-4}{13}\)
\(\dfrac{7}{21}+\dfrac{9}{-36}=\dfrac{1}{3}+\dfrac{1}{-4}=\dfrac{1}{3+\left(-4\right)}=\dfrac{1}{-1}=1\)
b) \(\dfrac{12}{20}-\dfrac{2}{5}=\dfrac{12}{20}+\left(\dfrac{-2}{5}\right)=\dfrac{3}{5}+\dfrac{-2}{5}=\dfrac{3+\left(-2\right)}{5}=\dfrac{1}{5}\)
\(\dfrac{2}{3}-\dfrac{-5}{6}=\dfrac{2}{3}+\dfrac{5}{6}=\dfrac{4}{6}+\dfrac{5}{6}=\dfrac{9}{6}=\dfrac{3}{2}\)
\(6-\dfrac{3}{20}=6+\dfrac{-3}{20}=\dfrac{60}{60}+\dfrac{-9}{60}=\dfrac{51}{60}\)
c) \(\dfrac{2}{21}.\dfrac{-7}{3}=\dfrac{2.\left(-1\right)}{7.3}=\dfrac{-2}{21}\)
\(\dfrac{27}{28}.\left(-21\right)=\dfrac{27.\left(-21\right)}{28}=\dfrac{-567}{28}\)
\(\dfrac{-15}{7}.\dfrac{-14}{25}=\dfrac{-3.\left(-2\right)}{1.5}=\dfrac{6}{5}\)
a) 15 . (27 + 18 + 6 ) + 15 . ( 23 +12 ) = 15. 51 + 15 . 35 = 765 + 525 = 1290
b) 14 . 35 . 5 + 10 . 25 . 7 + 20 . 70 = 2450 + 1750 + 1400 = 2452450
c) 53 . ( 51 + 4 ) + 53 . ( 49 + 96 ) + 53 = 53 . 55 + 53 . 145 + 53 = 2915 . 7685 = 22401775
d) 46 . ( 27 +75 ) +8 . ( 58 + 25 ) + 8 . ( 58 + 25 ) . 2 = 46 . 102 + 8 . 83 + 8 . 83 = 4692 + 664 + 664 = 6020
a,=128+62+25
=190+25
=215
b,=-75+[-5]+[-18]
=-80+[-18]
=-98
c,=21+14+15
=35+15
=50
d,[-12]+[-15]-25
=-27-25
=-52
e,=28+[-25]-10
=3-10=-7
f,=-1+2+[-30]+4+[-5]
=1+[-30]+{4+[-5]}
=-29+[-1]
=-30
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