Question

1) tính hợp lí ( nếu có thể ) 

c) \(\dfrac{2}{-11}\). 6\(\dfrac{2}{7}\)+ \(\dfrac{3}{7}\):3 + 5                d) 1,75 : 5 + 2,5 . ( \(4^2\)- 4. 4,1)

2) tìm x 

a) 1/2-x=-1/6           b) x+3,5=7,8-12,6:2            c) 7/35 = 35-x/-105

 

Answer 1

2: 

a: =>x=1/2+1/6=3/6+1/6=4/6=2/3

b: =>x+3,5=7,8-6,3=1,5

=>x=1,5-3,5=-2

c: =>(35-x)/-105=1/5

=>35-x=-21

=>x=56

Answer 2

1

c hình như tính bình thường thôi:v

d

= 1,75 : 5 + 2,5 . (16 – 4 . 4,1)

= 1,75 : 5 + 2,5 . (16 – 16,4)

= 1,75 : 5 + 2,5 . (−0,4)

= 0,35 − 1

= −0,65.

2

a

\(\Rightarrow x=\dfrac{1}{2}+\dfrac{1}{6}=\dfrac{3}{6}+\dfrac{1}{6}=\dfrac{4}{6}=\dfrac{2}{3}\)

b

\(\Rightarrow x+\dfrac{35}{10}=\dfrac{78}{10}-\dfrac{63}{5}:2\\ \Rightarrow x+\dfrac{35}{10}=\dfrac{78}{10}-\dfrac{63}{10}=\dfrac{15}{10}\\ \Rightarrow x=\dfrac{15}{10}-\dfrac{35}{10}=-2\)

c không rõ đề:v

Answer 3

\(1,\dfrac{2}{-11}.6\dfrac{2}{7}+\dfrac{3}{7}:3+5\\ =\dfrac{2}{-11}.\dfrac{44}{7}+\dfrac{3}{7}\times\dfrac{1}{3}+5\\ =-\dfrac{88}{77}+\dfrac{3}{21}+5\\ =-\dfrac{8}{7}+\dfrac{1}{7}+5\\ =-1+5\\ =4\)

\(d,1,75:5+2,5.\left(4^2-4.4,1\right)\\ =0,35+2,5.\left(16-16,4\right)\\ =0,35+2,5.0,4\\ =0,35+1\\ =1,35\)

`2,`

`a, 1/2 -x=-1/6`

`=> x= 1/2 -(-1/6)`

`=> x= 1/2 +1/6`

`=> x= 3/6+1/6`

`=>x= 4/6`

`=>x=2/3`

Vậy `x=2/3`

`b, x+3,5 =7,8 -12,6 :2`

`=> x+3,5 = 7,8 - 6,3`

`=> x+3,5=1,5`

`=> x= 1,5-3,5`

`=>x=-2`

Vậy `x=-2`

\(c,\dfrac{7}{35}=\dfrac{35-x}{-105}\\ \Rightarrow7.\left(-105\right)=35.\left(35-x\right)\\ \Rightarrow-735=1225-35x\\ \Rightarrow-735-1225=-35x\\ \Rightarrow-1960=-35x\\ \Rightarrow x=-1960:\left(-35\right)\\ \Rightarrow x=56\)

Vậy `x=56`

Answer 4

1, Mình tính thường nhé ạ, tại nhìn đề hình như tính bthường hết á cậu:').

\(c,\dfrac{2}{-11}\cdot6\dfrac{2}{7}+\dfrac{3}{7}:3+5=\dfrac{2}{-11}\cdot\dfrac{44}{7}+\dfrac{3}{7}\cdot\dfrac{1}{3}+5\)

\(=\dfrac{88}{-77}+\dfrac{3}{21}+5=\dfrac{8}{-7}+\dfrac{1}{7}+5=-1+5=4\)

`---`

\(d,1,75:5+2,5\cdot\left(4^2-4\cdot4,1\right)=0,35+2,5\cdot\left(16-16,4\right)\)

\(=0,35+2,5\cdot\left(0,4\right)=0,35+\left(-1\right)=-0,65\)

 

2,

\(a,\dfrac{1}{2}-x=-\dfrac{1}{6}\)

\(x=\dfrac{1}{2}-\left(-\dfrac{1}{6}\right)\)

\(x=\dfrac{6}{12}-\left(-\dfrac{2}{12}\right)\)

\(x=\dfrac{8}{12}=\dfrac{2}{3}\)

Vậy `x=2/3`

`---`

\(b,x+3,5=7,8-12,6:2\)

`x+3,5=7,8-6,3`

`x+3,5=1,5`

`x=1,5-3,5`

`x=-2`

Vậy `x=-2`

`---`

\(c,\dfrac{7}{35}=\dfrac{35-x}{-105}\)

\(\text{[}7\left(-105\right)\text{]}=35\left(35-x\right)\)

\(-735=35\left(35-x\right)\)

\(-\dfrac{735}{35}=35-x\)

\(-21=35-x\)

`x = 35 - (-21)`

`x = 35 + 21`

` x = 56`

Vậy `x=56`

#Tks_DN