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\(\frac{4}{5}+\frac{-7}{15}.1,25\)
\(=\frac{4}{5}+\frac{-7}{12}\)
\(=\frac{13}{60}\)
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1)-6,-14,-7,-3
2)a
3
a)(1/8+5):2/3
=41/5:2/3
=41/5x3/2=123/16
b)2/3x-13/35-2/7
=-26/105-2/7
=-8/15
B = ( \(\dfrac{5}{7}.0,6:3\dfrac{1}{2}\)) . ( 40% - 1,4) . \(\left(-2\right)^3\)
= (\(\dfrac{5}{7}.\dfrac{3}{5}\): \(\dfrac{7}{2}\)) . ( \(\dfrac{2}{5}-\dfrac{7}{5}\)) . (-8)
= (\(\dfrac{15}{35}:\dfrac{7}{2}\)) . \(\dfrac{-5}{5}\) . ( -8)
= (\(\dfrac{3}{7}.\dfrac{2}{7}\)) . (-1) . (-8)
= \(\dfrac{6}{49}\) . (-1) . (-8)
= \(\dfrac{-6}{49}\) . (-8)
= \(\dfrac{48}{49}\)
Vậy: B =\(\dfrac{48}{49}\)
Nhớ tick nha
B=(\(\dfrac{3}{7}.\dfrac{2}{7}\)).(\(\dfrac{4}{10}-\dfrac{14}{10}\)).(-8)
B=\(\dfrac{3}{7}.\left(-1\right)\left(-8\right)\)
B=\(\dfrac{24}{7}\)
a,3/7 +1/2-[-3]/70
=13/14 -[-3]/70
=65/70 -[-3]/70
=34/35
b,3/5+-1/25 -35/100
=14/25 - 35/100
=56 /100 -35/100
= 21/100
c ,5/12 -3/-16+3/4
=29/48 +3/4
= 29/48 +36/48
=65/48
d, 5/15 +4/-12 +1/7 -1/-6
= 1/3 +1/-3 +1/7-1/-6
=0+1/7-1/-6
= 13/42
A.\(\dfrac{3}{7}+\dfrac{1}{2}+\dfrac{\left(-3\right)}{70}\)
=\([\dfrac{30}{70}+\dfrac{\left(-3\right)}{70}]\)+\(\dfrac{1}{2}\)
= \(\dfrac{27}{70}+\dfrac{35}{70}\)
=\(\dfrac{62}{70}=\dfrac{31}{35}\)
B.\(\dfrac{3}{5}+\dfrac{-1}{25}-\dfrac{35}{100}\)
=\(\dfrac{60}{100}+\dfrac{-4}{100}-\dfrac{35}{100}\)
=\(\dfrac{60+\left(-4\right)-35}{100}\)
=\(\dfrac{21}{100}\)
C.\(\dfrac{5}{12}-\dfrac{3}{-16}+\dfrac{3}{4}\)
=\(\left(\dfrac{5}{12}+\dfrac{9}{12}\right)-\dfrac{-3}{16}\)
=\(\dfrac{7}{6}-\dfrac{-3}{16}\)
=\(\dfrac{56}{48}-\dfrac{-9}{48}\)=\(\dfrac{65}{48}\)
D.\(\dfrac{5}{15}+\dfrac{4}{-12}+\dfrac{1}{7}-\dfrac{1}{-6}\)
=\(\dfrac{1}{3}+\dfrac{1}{7}+(\dfrac{-2}{6}-\dfrac{-1}{6})\)
=\(\dfrac{1}{3}+\dfrac{1}{7}+\dfrac{-1}{6}\)
=\((\dfrac{1}{3}+\dfrac{-1}{6})+\dfrac{1}{7}\)
=\(\dfrac{1}{6}+\dfrac{1}{7}\)=\(\dfrac{13}{42}\)
Bài làm
a) \(\frac{5}{24}\)và \(\frac{7}{8}\)
Ta có: \(\frac{7}{8}=\frac{7.3}{8.3}=\frac{21}{24}\)
Vậy ta quy đồng hai phân số \(\frac{5}{24}\)và \(\frac{7}{8}\)ta được hai phân số mới là \(\frac{5}{24}\)và \(\frac{21}{24}\)
b) \(\frac{2}{3}\)và \(\left(-5\right)\)
Ta có: \(\left(-5\right)=\frac{\left(-5\right).3}{1.3}=-\frac{15}{3}\)
Vậy ta quy đồng hai phân số \(\frac{2}{3}\)và \(\left(-5\right)\)ta được hai phân số mới là \(\frac{5}{24}\)và \(\frac{21}{24}\)
c) \(\frac{5}{2^3.3}\)và \(\frac{7}{2^3.11}\)
Ta có: \(\frac{5}{2^3.3}=\frac{5}{8.3}=\frac{5}{24}=\frac{5.88}{24.88}=\frac{440}{2112}\)
\(\frac{7}{2^3.11}=\frac{7}{8.11}=\frac{7}{88}=\frac{7.24}{88.24}=\frac{168}{2112}\)
Vậy ta quy đồng hai phân số \(\frac{5}{2^3.3}\)và \(\frac{7}{2^3.11}\)ta được hai phân số mới là \(\frac{440}{2112}\)và \(\frac{168}{2112}\)
* Chú ý: Dấu " . " là dấu nhân. Ví dụ 2 . 3 = 2 x 3 = 6.
# Chúc bạn học tốt #
Bài 1
a) MC: 75
\(\frac{7}{-15}=\frac{-7}{15}=\frac{-7.5}{15.5}=\frac{-35}{75}\)
\(\frac{-8}{-25}=\frac{8}{25}=\frac{8.3}{25.3}=\frac{24}{75}\)
\(\frac{11}{-75}=\frac{-11}{75}\)
b) MC: 180
Cách làm tương tự
Bài 2:
\(\frac{-1}{8}=\frac{-3}{24}\)
\(\frac{2}{-3}=\frac{16}{-24}=\frac{-16}{24}\)
\(\frac{3}{-72}=\frac{1}{-24}=\frac{-1}{24}\)
\(\frac{5}{-6}=\frac{20}{-24}=\frac{-20}{24}\)
Bài 3:
\(1=\frac{16}{16}\)
\(\frac{5}{-8}=\frac{-10}{16}\)
\(0=\frac{0}{16}\)
a) \(\dfrac{2}{7}-\dfrac{1}{2}+\dfrac{5}{7}\)
\(=\left(\dfrac{2}{7}+\dfrac{5}{7}\right)-\dfrac{1}{2}\)
\(=\dfrac{7}{7}-\dfrac{1}{2}\)
\(=1-\dfrac{1}{2}\)
\(=\dfrac{1}{2}\)
b) \(\left(-4,8\right)-2,7+5,2\cdot3\)
\(=-4,8-2,7+15,6\)
\(=8,1\)
c) \(\left(-27,63\right)\cdot5,5+5,5\cdot\left(-72,37\right)-1,4\cdot5\)
\(=5,5\cdot\left(-27,63-72,37\right)-1,4\cdot5\)
\(=5,5\cdot\left(-100\right)-7\)
\(=-550-7\)
\(=-557\)
d) \(\dfrac{3}{5}:\left(2\dfrac{1}{3}\cdot\dfrac{6}{5}\right)\)
\(=\dfrac{3}{5}:\left(\dfrac{7}{3}\cdot\dfrac{6}{5}\right)\)
\(=\dfrac{3}{5}:\dfrac{7\cdot2}{5}\)
\(=\dfrac{3}{5}:\dfrac{14}{5}\)
\(=\dfrac{3}{5}\cdot\dfrac{5}{14}\)
\(=\dfrac{3}{14}\)