a.120-[7.20-(134-110).5]

=120-(7.20-24.5)

=120-(140-120)

=120-20

=100

b.1987-200.8+1005:5

=1987-1600+201

=588

C, 387.2694+7305.387+387

=387.(2694+7305+1)

=387.10000

3870 000

d, 

d.248:{[(368+232):120-3]+122}+2016

=248:{(600:120-3)+122}+2016

=248:(2+122)+2016

=248:144+2016

=2+2016

=2018

a)120-[7.20-(134-110).5]

=120-20

=100

b)1987-200.8+1005:5

=1987-1600+201

=588

c)387.2694+7305.387+387

=1042578+2827035+387

=3870000

d)248:{[368+232):120-3]+122}+2016

=248:124+2016

=2+2016

=2018

a)120-[7.20-(134-110).5]

=120-20

=100

b)1987-200.8+1005:5

=1987-1600+201

=588

c)387.2694+7305.387+387

=1042578+2827035+387

=3870000

d)248:{[368+232):120-3]+122}+2016

=248:124+2016

=2+2016

=2018

tích mình đi

ai tích mình 

mình tích lại 

thanks

\(120+2\left(3x-17\right)=214\)

\(120+6x-34=214\)

\(86+6x=214\)

\(6x=214-86\)

\(6x=128\)

\(x=128:6\)

\(x=\frac{64}{6}\)

\(120+2.\left(3.x-17\right)=214\)

\(2.\left(3.x-17\right)=214-120\)

\(2.\left(3.x-17\right)=94\)

\(3.x-17=94:2\)

\(3.x-17=47\)

\(3.x=47+17\)

\(3.x=64\)

\(x=64:3\)

\(x=\frac{64}{3}\)

Vậy \(x=\frac{64}{3}\)

Hình avata hơi bị chẹp đó =)))

Học tốt !!!

tui nè

Giúp mk vs, gấp lắm!!!

\(\left(x+1\right)+\left(x+2\right)+...+\left(x+10\right)=110\)

\(\left(x+x+...+x\right)+\left(1+2+3+...+10\right)=110\)

\(10x+55=110\)

\(10x=110-55\)

\(10x=55\)

\(x=55:10\)

\(x=5,5\)

\(10xX+\left(1+2+3+...+10\right)=110\)

\(1+2+3+...+10=\dfrac{10\left(1+10\right)}{2}=55\)

\(\Rightarrow10xX+55=110\Rightarrow10xX=55\)

\(\Rightarrow X=55:10=5,5\)

a) \(\frac{5}{6}+\frac{11}{12}+\frac{19}{20}+...+\frac{89}{90}\)

\(=1-\frac{1}{6}+1-\frac{1}{12}+...+1-\frac{1}{90}\)

\(=\left(1+1+1+...+1\right)-\left(\frac{1}{6}+\frac{1}{12}+...+\frac{1}{90}\right)\)

\(=\left(1+1+1+...+1\right)-\left(\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+...+\frac{1}{9\cdot10}\right)\)

Từ 2 đến 9 có : ( 9 - 2 ) / 1 + 1 = 8 ( số hạng ) => có 8 số 1

\(\Rightarrow8-\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{9}-\frac{1}{10}\right)\)

\(=8-\left(\frac{1}{2}-\frac{1}{10}\right)\)

\(=8-\frac{2}{5}=\frac{38}{5}\)

b) \(\frac{1}{2}+\frac{5}{6}+\frac{11}{12}+...+\frac{109}{110}\)

\(=1-\frac{1}{2}+1-\frac{1}{6}+...+1-\frac{1}{110}\)

\(=\left(1+1+1+...+1\right)-\left(\frac{1}{2}+\frac{1}{6}+...+\frac{1}{110}\right)\)

\(=\left(1+1+...+1\right)-\left(\frac{1}{1\cdot2}+\frac{1}{2\cdot3}+...+\frac{1}{10\cdot11}\right)\)

Từ 1 đến 10 có : ( 10 - 1 ) / 1 + 1 = 10 ( số hạng ) => có 10 số 1

\(\Rightarrow10-\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{10}-\frac{1}{11}\right)\)

\(=10-\left(1-\frac{1}{11}\right)\)

\(=10-\frac{10}{11}=\frac{100}{11}\)

100/11 nha

câu b bằng 891/110

câu a bằng 76/10

(x/-5+2/3);11/5-1,4.15/49=|-5|/21

(x/-5+2/3);11/5-1,4.15/49=5/21

(x/-5+2/3);11/5-21/49=5/21

(x/-5+2/3);11/5=5/21+21/49

(x/-5+2/3);11/5=35/147+63/147

(x/-5+2/3);11/5=35+63/147

(x/-5+2/3);11/5=98/147

x/-5+2/3=98/147.11/5

x/-5+2/3=98.11/147.5

x/-5+2/3=1078/735

x/-5+2/3=154/105

x/-5=154/105-2/3

x/-5=154/105-70/105

x/-5=154-70/105

x/-5=84/105

x/-5=-4/-5

suy ra x=-4

* la dau gi vay ban

dấu nhân

bn lm giúp mk với, mk k cho