Viết cách giải và tính :
a) 0,05+5-1/20
b) 6/15-7/8+3+3/5-2/16
giúp em với nha
K
Khách
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MN
30 tháng 4 2019
\(b,\frac{6}{15}-\frac{7}{8}+3+\frac{3}{5}+\frac{2}{16}\)
\(=\frac{2}{5}-\frac{7}{8}+3+\frac{3}{5}+\frac{1}{8}\)
\(=\left(\frac{2}{5}+\frac{3}{5}\right)+\left(-\frac{7}{8}+\frac{1}{8}\right)+3\)
\(=1+\left(-\frac{3}{4}\right)+3\)
\(=\frac{1}{4}+3\)
\(=3\frac{1}{4}\)
VT
20 tháng 8 2017
\(a,=\frac{7-1}{1.3.7}+\frac{9-3}{3.7.9}+\frac{13-7}{7.9.13}+\frac{15-9}{9.13.15}\)\(+\frac{19-13}{13.15.19}\)
\(=\frac{1}{1.3}-\frac{1}{3.7}+\frac{1}{3.7}-\frac{1}{7.9}+\frac{1}{7.9}-\frac{1}{9.13}+\frac{1}{9.13}-\frac{1}{13.15}+\frac{1}{13.15}-\frac{1}{15.19}\)
\(=\frac{1}{1.3}-\frac{1}{15.19}=\frac{95}{285}-\frac{1}{285}=\frac{94}{285}\)
\(b,=\frac{1}{6}.\left(\frac{6}{1.3.7}+\frac{6}{3.7.9}+\frac{6}{7.9.13}+\frac{6}{9.13.15}+\frac{6}{13.15.19}\right)\)
làm giống như trên
\(c,=\frac{1}{8}.\left(\frac{1}{1.2.3}+\frac{1}{2.3.4}+\frac{1}{3.4.5}+...+\frac{1}{48.49.50}\right)\)
\(=\frac{1}{16}.\left(\frac{2}{1.2.3}+\frac{2}{2.3.4}+\frac{2}{3.4.5}+...+\frac{2}{48.49.50}\right)\)
\(=\frac{1}{16}.\left(\frac{3-1}{1.2.3}+\frac{4-2}{2.3.4}+\frac{5-3}{3.4.5}+...+\frac{50-48}{48.49.50}\right)\)
\(=\frac{1}{16}.\left(\frac{1}{1.2}-\frac{1}{2.3}+\frac{1}{2.3}-\frac{1}{3.4}+\frac{1}{3.4}-\frac{1}{4.5}+...+\frac{1}{48.49}-\frac{1}{49.50}\right)\)
\(=\frac{1}{16}.\left(\frac{1}{2}-\frac{1}{2450}\right)=\frac{1}{16}.\left(\frac{1225}{2450}-\frac{1}{2450}\right)=\frac{153}{4900}\)
\(d,=\frac{5}{7}.\left(\frac{7}{1.5.8}+\frac{7}{5.8.12}+\frac{7}{8.12.15}+...+\frac{7}{33.36.40}\right)\)
\(=\frac{5}{7}.\left(\frac{8-1}{1.5.8}+\frac{12-5}{5.8.12}+\frac{15-8}{8.12.15}+...+\frac{40-33}{33.36.40}\right)\)
\(=\frac{5}{7}.\left(\frac{1}{1.5}-\frac{1}{5.8}+\frac{1}{5.8}-\frac{1}{8.12}+\frac{1}{8.12}-\frac{1}{12.15}+...+\frac{1}{33.36}-\frac{1}{36.40}\right)\)
\(=\frac{5}{7}.\left(\frac{1}{5}-\frac{1}{1440}\right)=\frac{5}{7}.\left(\frac{288}{1440}-\frac{1}{1440}\right)=\frac{41}{288}\)
P/S: . là nhân nha
NN
13 tháng 3 2022
a) 4+2/5=22/5
b) 5/4+2=13/4
c) 3+3/2=9/2
d) 3/4-1/8=5/8
e) 17/15-7/10=13/30
g) 25/12-15/8=5/24
h) 5-4/3=11/3
i)15/4-3=3/4
13 tháng 3 2022
a)\(\dfrac{4}{1}+\dfrac{2}{5}=\dfrac{20}{5}+\dfrac{2}{5}=\dfrac{22}{5}\)
b)\(\dfrac{5}{4}+\dfrac{2}{1}=\dfrac{5}{4}+\dfrac{8}{4}=\dfrac{13}{4}\)
c)\(\dfrac{3}{1}+\dfrac{3}{2}=\dfrac{6}{2}+\dfrac{3}{2}=\dfrac{9}{2}\)
d)\(\dfrac{3}{4}-\dfrac{1}{8}=\dfrac{6}{8}-\dfrac{1}{8}=\dfrac{5}{8}\)
e)\(\dfrac{17}{15}-\dfrac{7}{10}=\dfrac{34}{30}-\dfrac{21}{30}=\dfrac{13}{30}\)
g)\(\dfrac{25}{12}-\dfrac{15}{8}=\dfrac{50}{24}-\dfrac{45}{24}=\dfrac{5}{24}\)
h)\(\dfrac{5}{1}-\dfrac{4}{3}=\dfrac{15}{3}-\dfrac{4}{3}=\dfrac{11}{3}\)
i)\(\dfrac{15}{4}-\dfrac{3}{1}=\dfrac{15}{4}-\dfrac{12}{4}=\dfrac{3}{4}\)
29 tháng 6 2023
a: 14/5-7/5=7/5
b: 7/8-1/3+5/4
=21/24-8/24+30/24
=43/24
c; =7/6+5/6+2/15+13/15
=2+1
=3
d: =4*5/3*11=20/33
e: =2/9*1/6*1/4=2/9*1/24=1/108
2:
a: \(=\dfrac{3}{9}\cdot\dfrac{4}{4}\cdot\dfrac{5}{5}\cdot\dfrac{6}{6}\cdot\dfrac{7}{7}=\dfrac{1}{3}\)
b: \(=\dfrac{1}{6}\left(\dfrac{22}{3}-\dfrac{2}{3}\right)=\dfrac{10}{3}\cdot\dfrac{1}{6}=\dfrac{10}{18}=\dfrac{5}{9}\)
c; \(=\dfrac{1}{3}\left(9-\dfrac{2}{5}-\dfrac{3}{5}\right)=\dfrac{8}{3}\)
\(0,05+5-\dfrac{1}{20}=0,05+5-0,05=5\)
\(\dfrac{6}{15}-\dfrac{7}{8}+3+\dfrac{3}{5}-\dfrac{2}{16}=\dfrac{2}{.5}-\dfrac{7}{8}+3+\dfrac{3}{5}-\dfrac{1}{8}=1-1+3=3\)
a) \(0.05+5-\dfrac{1}{20}=\dfrac{1}{20}+5-\dfrac{1}{20}=5\)
b) \(\dfrac{6}{15}-\dfrac{7}{8}+3+\dfrac{3}{5}-\dfrac{2}{16}=1-1+3=3\)