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17 tháng 7 2018

a, -51   b, -40

2:

a: =4+3/8+5+2/3

=9+3/8+2/3

=216/24+9/24+16/24

=216/24+25/24

=241/24

b; =2+3/8+1+1/4+3+6/7

=6+3/8+1/4+6/7

=6+5/8+6/7

=419/56

c: \(=2+\dfrac{3}{8}-1-\dfrac{1}{4}+5+\dfrac{1}{3}\)

=6+3/8-1/4+1/3

=6+1/8+1/3

=6+11/24

=155/24

d: \(=3+\dfrac{5}{6}+6\cdot\dfrac{13}{6}\)

=3+13+5/6

=16+5/6

=101/6

e: =3+1/2+4+5/7-5-5/14

=3+4-5+1/2+5/7-5/14

=2+7/14+10/14-5/14

=2+12/14

=2+6/7=20/7

f: =9/2+1/2:11/2

=9/2+1/11

=99/22+2/22=101/22

7 × 3 mu x + 20 × 3 mu x = 3 mu 25

a) \(\frac{3}{5}+\frac{7}{10}+\frac{-13}{20}=\frac{12}{20}+\frac{14}{20}+\frac{-13}{20}=\frac{12+14+\left(-13\right)}{20}=\frac{13}{20}\)

b) \(\frac{1}{2}+\frac{-1}{5}+\frac{1}{4}+\frac{1}{6}=\frac{60}{120}+\frac{-24}{120}+\frac{30}{120}+\frac{20}{120}\)\(=\frac{60+\left(-24\right)+30+20}{120}=\frac{86}{120}=\frac{43}{60}\)

c) \(\frac{2}{3}+\frac{-3}{4}+\frac{5}{8}+\frac{-1}{2}\)\(=\frac{16}{24}+\frac{-18}{24}+\frac{15}{24}+\frac{-12}{24}\)\(=\frac{16+\left(-18\right)+15+\left(-12\right)}{24}=\frac{1}{24}\)

4 tháng 3 2019

\(a)\frac{3}{5}+\frac{7}{10}+\frac{-13}{20}\)

\(\frac{3}{5}+\frac{7}{10}+\frac{-13}{20}=\frac{3.4}{5.4}+\frac{7.2}{10.2}+\frac{-12}{20}\)

\(=\frac{12}{20}+\frac{14}{20}+\frac{-13}{20}=\frac{12+14+\left(-13\right)}{20}\)

\(=\frac{13}{20}\)

\(b)\frac{1}{2}+\frac{-1}{5}+\frac{1}{4}+\frac{1}{6}\)

\(\frac{1}{2}+\frac{-1}{5}+\frac{1}{4}+\frac{1}{6}=\frac{1.30}{2.30}+\frac{-1.12}{5.12}+\frac{1.15}{4.15}+\frac{1.10}{6.10}\)

\(=\frac{30}{60}+\frac{-12}{60}+\frac{15}{60}+\frac{10}{60}=\frac{30+\left(-12\right)+15+10}{60}\)

\(=\frac{43}{60}\)

\(c)\frac{2}{3}+\frac{-3}{4}+\frac{5}{8}+\frac{-1}{2}\)

\(\frac{2}{3}+\frac{-3}{4}+\frac{5}{8}+\frac{-1}{2}=\frac{2.8}{3.8}+\frac{-3.6}{4.6}+\frac{5.3}{8.3}+\frac{-1.12}{2.12}\)

\(=\frac{16}{24}+\frac{-18}{24}+\frac{15}{24}+\frac{-12}{24}\)\(=\frac{16+\left(-18\right)+15+\left(-12\right)}{24}\)

\(=\frac{1}{24}\)

 Nếu có sai chỗ nào thì báo lỗi cho tớ nhé!

Chúc cậu một buổi tối vui vẻ ~!!!!!!!!!!!

#0006

30 tháng 4 2017

a) - 10 b) - 1009

c) Ta có: \(\dfrac{3}{5}+\dfrac{-5}{20}+\dfrac{30}{75}+\dfrac{-7}{4}\)

\(=\dfrac{3}{5}+\dfrac{2}{5}+\dfrac{-1}{4}+\dfrac{-7}{4}\)

\(=1-2=-1\)

Giải:

a)-1/12+4/3=-1/12+16/12=15/12=5/4

b)(-4/14-3/15)-(1/5-20/35-(-1)).7

=-17/35-22/35.7

=-17/35-22/5

=-171/35

c)3/5+-5/20+30/75+-7/4

=3/5+-1/4+2/5+-7/4

=(3/5+2/5)+(-1/4+-7/4)

=1+-2

=-1

d)5/6.-12/14+7/13

=-5/7+7/13

=-16/91

e)2/-9-5/-36-1/4

=-1/12-1/4

=-1/3

f)2/23+-5/12+7/18+21/23+-7/12

=(2/23+21/23)+(-5/12+-7/12)+7/18

=1+-1+7/18

=7/18