|-3/11|.4/15.|-11/3.(-30).. giúp vói ạ
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a: =-5/9-4/9+8/15+7/15-2/11=-2/11
b: =10/17+7/17-5/13-8/13+11/25
=11/25
c: =(9/12-2/12)*3/2=7/12*3/2=21/24=7/8
d: =(31/10-25/10)*3-2
=3/5*3-2
=9/5-2
=-1/5
10/11+9/10 = 199/110
15/30+7/30 = 11/15
1/2+1/3 = 5/6
3/5+11/15 = 4/3
3/4+1/6 = 11/12
5/11+4/11 = 9/11
BẠN THẬT XUẤT SẮC
CẢM ƠN BẠN NHA
CHÚC BAN CUỐI TUẦN VUI VẺ
\(\dfrac{21}{36}-\left(-\dfrac{11}{30}\right)=\dfrac{7}{12}+\dfrac{11}{30}=\dfrac{7.5+11.2}{60}=\dfrac{57}{60}=\dfrac{19}{20}\\ ----\\\dfrac{-4}{8}+\left(-\dfrac{3}{10}\right)=\dfrac{-1}{2}-\dfrac{3}{10}=\dfrac{-1.5-3}{10}=\dfrac{-8}{10}=-\dfrac{4}{5}\\ ----\\ \dfrac{7}{12}-\left(-\dfrac{9}{20}\right)=\dfrac{7}{12}+\dfrac{9}{20}=\dfrac{7.5+9.3}{60}=\dfrac{62}{60}=\dfrac{31}{30}\\ ---\\ \dfrac{-2}{5}+\left(-\dfrac{11}{30}\right)=-\dfrac{2}{5}-\dfrac{11}{30}=\dfrac{-2.6-11}{30}=-\dfrac{29}{30}\)
Câu 1 ) Sắp xếp theo thứ tự từ bé đến lớn
11 phần 18;7 phần 9;14 phần 15
Câu 2 ) Sắp xếp theo thứ tự từ bé đến lớn
8 phần 9;15 phần 11;9 phần 5
Câu 3 ) So sánh
3 phần 4 < 5 phần 9
Câu 4 ) So sánh
8 phần 12 < 25 phần 30
Như lời hứa nhớ k nha
\(\left(-\dfrac{1}{2}\right)^2\div\dfrac{1}{4}-2\times\left(-\dfrac{1}{2}\right)^2\\= \dfrac{1}{4}\div\dfrac{1}{4}-2\times\dfrac{1}{4}\\ =1-\dfrac{1}{2}\\ =\dfrac{1}{2}\)
\(\left(-2\right)^3\times-\dfrac{1}{24}+\left(\dfrac{4}{3}-1\dfrac{5}{6}\right)\div\dfrac{5}{12}\)
= \(-6\times-\dfrac{1}{24}+\left(\dfrac{4}{3}-\dfrac{11}{6}\right)\div\dfrac{5}{12}\)
= \(\dfrac{1}{4}+-\dfrac{1}{2}\div\dfrac{5}{12}\)
= \(\dfrac{1}{4}+-\dfrac{6}{5}\)
= \(\dfrac{1}{4}-\dfrac{6}{5}\)
= \(-\dfrac{19}{20}\)
\(\left(6\dfrac{4}{9}+\dfrac{7}{11}\right)-\left(4\dfrac{4}{9}-2\dfrac{4}{11}\right)\\ =\dfrac{58}{9}+\dfrac{7}{11}-\dfrac{40}{9}+\dfrac{26}{11}\\ =\dfrac{58}{9}-\dfrac{40}{9}+\dfrac{7}{11}+\dfrac{26}{11}\\ =12+3\\ =15\)
\(a,\left(\dfrac{-1}{2}\right)^2:\dfrac{1}{4}-2\left(-\dfrac{1}{2}\right)^2\)
\(=\left(-\dfrac{1}{2}\right)^2\left(4-2\right)\)
\(=\dfrac{1}{4}.2=\dfrac{1}{2}\)
\(b,\left(-2\right)^3.\dfrac{-1}{24}+\left(\dfrac{4}{3}-1\dfrac{5}{6}\right):\dfrac{5}{12}\)
\(=\left(-8\right).\dfrac{-1}{24}+\left(-\dfrac{1}{2}\right).\dfrac{12}{5}\)
\(=\dfrac{1}{3}+\left(-\dfrac{1}{5}\right)=\dfrac{2}{15}\)
\(c,\left(6\dfrac{4}{9}+\dfrac{7}{11}\right)-\left(4\dfrac{4}{9}-2\dfrac{4}{11}\right)\)
\(=\dfrac{701}{99}-\dfrac{206}{99}=\dfrac{495}{99}=5\)
\(d,10\dfrac{1}{5}-5\dfrac{1}{2}.\dfrac{60}{11}+\dfrac{3}{15\%}\)
\(=\dfrac{51}{5}-30+20=\dfrac{1}{5}\)
\(e,\dfrac{5}{7}.\dfrac{5}{11}+\dfrac{5}{7}.\dfrac{2}{11}-\dfrac{5}{7}.\dfrac{14}{11}\)
\(=\dfrac{5}{7}\left(\dfrac{5}{11}+\dfrac{2}{11}-\dfrac{14}{11}\right)=\dfrac{5}{7}.\left(-\dfrac{7}{11}\right)\)
\(=-\dfrac{5}{11}\)
\(f,\dfrac{-5}{7}.\dfrac{2}{11}+\left(-\dfrac{5}{7}\right).\dfrac{9}{11}+1\dfrac{5}{7}\)
\(=\left(-\dfrac{5}{7}\right)\left(\dfrac{2}{11}+\dfrac{9}{11}\right)+\dfrac{12}{7}\)
\(=\left(-\dfrac{5}{7}\right)+\dfrac{12}{7}=1\)
a) \(B=\frac{3}{2.5}+\frac{3}{5.8}+\frac{3}{8.11}+\frac{3}{11.14}\)
\(=\frac{1}{2}-\frac{1}{5}+\frac{1}{5}-\frac{1}{8}-\frac{1}{8}+\frac{1}{11}+\frac{1}{11}-\frac{1}{14}\)
\(=\frac{1}{2}-\frac{1}{14}=\frac{3}{7}\)
b) Ta có : A = \(\frac{3}{1.2}+\frac{3}{2.3}+\frac{3}{3.4}+...+\frac{3}{99.100}\)
\(=3.\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{99}-\frac{1}{100}\right)\)
\(=3.\left(1-\frac{1}{100}\right)\)
\(=3.\frac{99}{100}=\frac{297}{100}\)
\(\dfrac{1}{2}+\dfrac{3}{4}-\left(\dfrac{3}{4}-\dfrac{4}{5}\right)\)
=\(\dfrac{1}{2}+\dfrac{3}{4}-\dfrac{3}{4}+\dfrac{4}{5}\)
=\(\left(\dfrac{1}{2}+\dfrac{4}{5}\right)+\left(\dfrac{3}{4}-\dfrac{3}{4}\right)\)
=\(\left(\dfrac{5}{10}+\dfrac{8}{10}\right)+0\)
=\(\dfrac{13}{10}\)
\(-\dfrac{7}{25}.\dfrac{11}{13}+\left(-\dfrac{7}{25}\right).\dfrac{2}{13}-\dfrac{18}{25}\)
=\(-\dfrac{7}{25}.\cdot\left(\dfrac{11}{13}+\dfrac{2}{13}\right)-\dfrac{18}{25}\)
=\(-\dfrac{7}{25}.1-\dfrac{18}{25}\)
=\(-\dfrac{7}{25}-\dfrac{18}{25}\)
=\(-\dfrac{25}{25}\) = \(-1\)
1)C= 1/5+1/10+1/20+1/40+...+1/1280
\(=\frac{1}{5}\left(1+\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^8}\right)\)
Đặt cái trong ngoặc là A ta có:\(2A=2+1+...+\frac{1}{2^7}\)
\(2A-A=\left(2+1+...+\frac{1}{2^7}\right)-\left(1+\frac{1}{2}+...+\frac{1}{2^8}\right)\)
\(A=2-\frac{1}{2^8}\).Thay A vào ta được:\(C=\frac{1}{5}\left(2-\frac{1}{2^8}\right)=\frac{1}{5}\cdot\frac{511}{256}=\frac{511}{1280}\)
2)D= 2/1*3+2/3*5+2/5*10+2/7*9+2/9*11+2/11*18+2/13*15
\(=1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+...+\frac{1}{13}-\frac{1}{15}\)
\(=1-\frac{1}{15}\)
\(=\frac{14}{15}\)
3)E= 4/3*7+4/7*11+4/11*15+4/15*19+4/19*23+4/23*27
\(=\frac{1}{3}-\frac{1}{7}+\frac{1}{7}-\frac{1}{11}+...+\frac{1}{23}-\frac{1}{27}\)
\(=\frac{1}{3}-\frac{1}{27}\)
\(=\frac{8}{27}\)
4)G= 1/2+1/6+1/12+1/20+1/30+1/42+...+1/110
\(=\frac{1}{1.2}+\frac{1}{2.3}+...+\frac{1}{10.11}\)
\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{10}-\frac{1}{11}\)
\(=1-\frac{1}{11}\)
\(=\frac{10}{11}\)
5)H= 3/1*2+3/2*3+3/3*4+3/4*5+...+3/9*10
\(=3\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{9}-\frac{1}{10}\right)\)
\(=3\left(1-\frac{1}{10}\right)\)
\(=3\times\frac{9}{10}\)
\(=\frac{27}{10}\).Lần sau bạn đăng ít một thôi nhé
\(a,\frac{3}{20}=\frac{3\times3}{20\times3}=\frac{9}{60}\)
\(\frac{7}{30}=\frac{7\times2}{30\times2}=\frac{14}{60}\)
\(\frac{4}{15}=\frac{4\times4}{15\times4}=\frac{16}{60}\)
\(c,\frac{7}{-30}=\frac{7\times4}{\left(-30\right)\times4}=\frac{28}{-120}\)
\(\frac{3}{-40}=\frac{3\times3}{\left(-40\right)\times3}=\frac{9}{-120}\)
\(-\frac{11}{30}=\frac{\left(-11\right)\times4}{30\times4}=-\frac{44}{120}\)
1)\(\dfrac{2}{9}+\dfrac{-3}{4}+\dfrac{5}{30}\)
\(=\dfrac{2.20}{9.20}+\dfrac{-3.45}{4.45}+\dfrac{5.6}{30.6}\)
\(=\dfrac{40}{180}+\dfrac{-135}{180}+\dfrac{30}{180}\)
\(=\dfrac{40+\left(-135\right)+30}{180}\)
\(=\dfrac{-65}{180}\)
\(=\dfrac{-13}{36}\)
2)\(\dfrac{-7}{12}-\dfrac{11}{18}\)
\(=\dfrac{-7.3}{12.3}-\dfrac{11.2}{18.2}\)
\(=\dfrac{-21}{36}-\dfrac{22}{36}\)
\(=\dfrac{-21-22}{36}\)
\(=\dfrac{-43}{36}\)
3)\(\dfrac{7}{8}-\dfrac{-5}{16}\)
\(=\dfrac{7.2}{8.2}-\dfrac{-5}{16}\)
\(=\dfrac{14}{16}-\dfrac{-5}{16}\)
\(=\dfrac{14-\left(-5\right)}{16}\)
\(=\dfrac{19}{16}\)
4)\(\dfrac{3}{8}-\dfrac{-9}{10}-\dfrac{5}{16}\)
\(=\dfrac{3.10}{8.10}-\dfrac{-9.8}{10.8}-\dfrac{5.5}{16.5}\)
\(=\dfrac{30}{80}-\dfrac{-72}{80}-\dfrac{25}{80}\)
\(=\dfrac{30-\left(-72\right)-25}{80}\)
\(=\dfrac{77}{80}\)
1) x+14=43x+14=43
⇒x=43−14=1312⇒x=43−14=1312
2) 34:25.x=296034:25.x=2960
⇒25.x=2960−34=−415⇒25.x=2960−34=−415
⇒x=−415.52=−23⇒x=−415.52=−23
3) 134.x+112=−45134.x+112=−45
⇒74.x+32=−45⇒74.x+32=−45
⇒74.x=−45−32=−2310⇒74.x=−45−32=−2310
⇒x=−2310.47=−−4635⇒x=−2310.47=−−4635
4) 1112−(25+x)=231112−(25+x)=23
⇒25+x=1112−23=14⇒25+x=1112−23=14
⇒x=14−25=−320⇒x=14−25=−320
5) 234.x=317:0,01234.x=317:0,01
⇒114.x=117:1100=11007⇒114.x=117:1100=11007
⇒x=11007.411=447⇒x=11007.411=447
6) 2x.(x−17)=02x.(x−17)=0
⇒x−17=0⇒x−17=0 (1) hoặc x=0x=0
(1) ⇒x=17⇒x=17
Vậy x={0;17}x={0;17}
7) 34+14:x=2534+14:x=25
⇒14:x=25−34=−720⇒14:x=25−34=−720
⇒x=14:−720=14.−207=−57⇒x=14:−720=14.−207=−57
8) 3,8:2x=14:2233,8:2x=14:223
⇒1,9x=14:83=14.38=332⇒1,9x=14:83=14.38=332
⇒x=332:1,9=15304⇒x=332:1,9=15304
9) 0,25x:3=56:0,125=56:18=56.8=2030,25x:3=56:0,125=56:18=56.8=203
⇒0,25x=203.3=20⇒0,25x=203.3=20
⇒x=20:0,25=80⇒x=20:0,25=80
10) 113:0,8=23:0,1x113:0,8=23:0,1x
⇒43:45=23:110.x⇒43:45=23:110.x
⇒53=203.x⇒53=203.x
⇒x=53:203=14⇒x=53:203=14
11) 3,2x+(−1,2)x+2,7=−4,93,2x+(−1,2)x+2,7=−4,9
⇒2x+2,7=−4,9⇒2x+2,7=−4,9
⇒2x=−4,9−2,7=−7,6⇒2x=−4,9−2,7=−7,6
⇒x=−3,8⇒x=−3,8
12) |x|−2,2=1,3|x|−2,2=1,3
⇒|x|=1,3+2,2=3,5⇒|x|=1,3+2,2=3,5
⇒x=±3,5⇒x=±3,5
13) |x+34|−13=0|x+34|−13=0
⇒|x+34|=13⇒|x+34|=13
⇒x+34=13⇒x=−512⇒x+34=13⇒x=−512
hoặc x+34=−13⇒x=−1312x+34=−13⇒x=−1312
Vậy x={−512;−1312}x={−512;−1312}
14) |x+13|−4=−1|x+13|−4=−1
⇒|x+13|=−1+4=3⇒|x+13|=−1+4=3
⇒x+13=3⇒x=83⇒x+13=3⇒x=83
Hoặc x+13=−3⇒x=−3−13=−103x+13=−3⇒x=−3−13=−103
15) Do |x−1,5|≥0|x−1,5|≥0 và |2,5−x|≥0|2,5−x|≥0 với mọi giá trị của xx
⇒|x−1,5|+|2,5−x|=0⇒|x−1,5|+|2,5−x|=0 khi
⇒x−1,5=0⇒x=1,5⇒x−1,5=0⇒x=1,5 và 2,5−x=0⇒x=2,52,5−x=0⇒x=2,5 (loại vì ra 2 kết quả khác nhau)