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B7 chu vi mảnh vườn là 3,3 m
diện tích là \(\dfrac{8}{7}\)m vuông
Bài 7:
Chu vi là:
\(\left(\dfrac{12}{5}+\dfrac{10}{21}\right)\cdot2=\dfrac{604}{105}\left(m\right)\)
Diện tích là:
\(\dfrac{12}{5}\cdot\dfrac{10}{21}=\dfrac{8}{7}\left(m^2\right)\)
a: =-3/4+1/2-1/13+3/13=-1/4+2/13=-13/52+8/52=-5/52
b: =10/11+1/11-1/8=1-1/8=7/8
c: =4(2,86+3,14)-30,05+9x0,75
=24-30,05+6,75
=0,7
\(\left(\frac{10}{99}+\frac{11}{199}-\frac{12}{299}\right)\times\left(\frac{1}{2}-\frac{1}{3}+-\frac{1}{6}\right)\)
\(=\left(\frac{10}{99}+\frac{11}{199}-\frac{12}{299}\right)\times\left(\frac{1}{2}-\frac{1}{3}-\frac{1}{6}\right)\)
\(=\left(\frac{10}{99}+\frac{11}{199}-\frac{12}{299}\right)\times\left(\frac{3}{6}-\frac{2}{6}-\frac{1}{6}\right)\)
\(=\left(\frac{10}{99}+\frac{11}{199}-\frac{12}{299}\right)\times0\)
\(=0\)
a: \(=\dfrac{1}{3}+\dfrac{1}{8}-\dfrac{3}{16}\cdot4=\dfrac{11}{24}-\dfrac{3}{64}=\dfrac{88}{192}-\dfrac{9}{192}=\dfrac{79}{192}\)
b: \(=\dfrac{5}{8}\cdot\left(-16\right)=-10\)
c: \(=\left(\dfrac{8}{5}+\dfrac{1}{3}\right):\dfrac{29}{5}-\dfrac{4}{81}\cdot9\)
\(=\dfrac{29}{15}\cdot\dfrac{5}{29}-\dfrac{4}{9}=\dfrac{1}{3}-\dfrac{4}{9}=-\dfrac{1}{9}\)
\(1,\dfrac{9}{17}.\dfrac{2}{7}+\dfrac{9}{17}.\dfrac{5}{7}=\dfrac{9}{17}\left(\dfrac{2}{7}+\dfrac{5}{7}\right)=\dfrac{9}{17}.1=\dfrac{9}{17}\)
\(2,\dfrac{-5}{9}.\dfrac{13}{28}-\dfrac{13}{28}.\dfrac{4}{9}=\dfrac{13}{28}\left(\dfrac{-5}{9}-\dfrac{4}{9}\right)=\dfrac{13}{28}.\left(-1\right)=\dfrac{-13}{28}\)
\(3,\dfrac{-1}{3}.\dfrac{1}{5}+\dfrac{1}{3}.\dfrac{1}{2}=\dfrac{1}{3}.\dfrac{-1}{5}+\dfrac{1}{3}.\dfrac{1}{2}=\dfrac{1}{3}\left(\dfrac{-1}{5}+\dfrac{1}{2}\right)=\dfrac{1}{3}.\dfrac{3}{10}=\dfrac{1}{10}\)
cam on ban