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\(\left(\frac{3}{10}-\frac{4}{15}-\frac{7}{20}\right).\frac{5}{19}=-\frac{19}{20}.\frac{5}{19}=-\frac{1}{4}\)
\(\left(\frac{1}{14}+\frac{1}{7}-\frac{-3}{35}\right).\frac{-4}{3}=\frac{3}{10}.-\frac{4}{3}=-\frac{4}{10}=-\frac{2}{5}\)
\(x:\frac{1}{7}=14\)
=> \(x=14\times\frac{1}{7}\)
=> x = 2
Vậy x = 2
\(\frac{8}{x}=\frac{20}{15}\)
=> \(\frac{8}{x}=\frac{4}{3}=\frac{8}{6}\)
=> x = 6
Vậy x = 6
\(52\times\frac{x}{78}=3380\)
=> \(\frac{x}{78}=3380:52\)
=> \(\frac{x}{78}=65\)
=> x = 65 x 78
=> x = 5070
Vậy x = 5070
a)<=>2/7:(13/24+5/24) b)<=>15/24-9/24-4/24 c)=7.5.39/13.14.15
<=>2/7:3/4 <=>2/24=1/12 =3/2.3
<=>2/7x4/3 =1/2
<=>8/21
a. \(\frac{2}{7}:\frac{13}{24}+\frac{2}{7}:\frac{5}{24}\)
= \(\frac{2}{7}:\left(\frac{13}{24}+\frac{5}{24}\right)\)
= \(\frac{2}{7}:\frac{3}{4}\)
= \(\frac{8}{21}\)
b. \(\frac{15}{24}-\frac{3}{8}-\frac{1}{6}\)
= \(\frac{15}{24}-\frac{9}{24}-\frac{4}{24}\)
= \(\frac{2}{24}=\frac{1}{12}\)
c. \(\frac{7}{13}.\frac{5}{14}.\frac{39}{15}\)
= \(\frac{7.5.3.13}{13.2.7.3.5}\)
= \(\frac{1}{2}\)
ta có \(\frac{11.3^{22}.3^7-9^{15}}{\left(2.3^{14}\right)^2}=\frac{11.3^{29}-\left(3^2\right)^{15}}{2^2.\left(3^{14}\right)^2}\)
= \(\frac{11.3^{29}-3^{30}}{2^2.3^{28}}=\frac{3^{29}\left(11-3\right)}{2^2.3^{28}}\)
= \(\frac{3^{29}.2^3}{2^2.3^{28}}=3.2=6\)
\(\frac{14}{6}+\frac{1}{3}+\frac{14}{14}+\frac{14}{9}+\frac{7}{15}+\frac{6}{4}\)
\(=\frac{14}{6}+\frac{1}{3}+\frac{14}{9}+\frac{7}{15}+\frac{14}{14}+\frac{6}{4}\)
\(=\frac{42+6+28}{18}+\frac{7}{15}+\frac{2}{2}+\frac{3}{2}\)
\(=\frac{76}{18}+\frac{7}{15}+\frac{5}{2}\)
\(=\frac{76}{18}+\frac{5}{2}+\frac{7}{15}\)
\(=\frac{76+45}{18}+\frac{7}{15}\)
\(=\frac{121}{18}+\frac{7}{15}\)
\(=\frac{605+42}{90}\)
\(=\frac{647}{90}\)
\(\frac{14}{6}+\frac{1}{3}+\frac{14}{14}+\frac{14}{9}+\frac{7}{15}+\frac{6}{4}\)
\(=(\frac{7}{3}+\frac{1}{3})+1+(\frac{14}{9}+\frac{7}{15})+\frac{3}{2}\)
\(=\frac{8}{3}+1+\frac{91}{45}+\frac{3}{2}\)
\(=2+\frac{2}{3}+1+2+\frac{1}{45}+1+\frac{1}{2}\)
\(=\left(\frac{2}{3}+\frac{1}{45}+\frac{1}{2}\right)+\left(2+1+2+1\right)\)
\(=1+\frac{17}{90}+6\)
\(=7+\frac{17}{90}\)
\(=7\frac{17}{90}\)
Bài 1 :
a ) \(\frac{17}{7}+\frac{6}{5}-\frac{20}{15}\)
= \(\frac{17}{7}+\frac{18}{15}-\frac{20}{15}\)
= \(\frac{17}{7}-\left(\frac{20}{15}-\frac{18}{15}\right)\)
= \(\frac{17}{7}-\frac{2}{15}\)
= \(\frac{241}{105}\)
Từ bé đến lớn : 13/14;14/15;15/16;16/17;17/18;18/19;19/20
Chúc bạn học tốt nhé!!!
