19/20x2/100+19/20x2/100

= [19/20+19/20]x2/100

= 38/20x2/100

= 19/500

75/76x102/100-75/76x2/100

= [102/100-2/100]x75/76

= 1x75/76

= 75/76

3x7/10+7/10x5+2x7/10

= [3+5+2]x7/10

= 10x7/10

= 7

giá trị biểu thức 

2/5+2/3x3/4

= 2/5+1/6

= 17/30

1/2x1/3-1/8

= 1/6-1/8

= 1/24

[1/2+1/3]:3/9

= 5/6:3/9

= 5/2

                       nhớ tick cho tớ nhé

rùi đó

\(1\frac{1}{2}+x=\frac{3}{2}-7\)

<=> \(\frac{3}{2}+x=\frac{-11}{2}\)

<=> \(x=-7\)

\(\frac{1}{4}+\frac{1}{3}:3x=-5\)

<=> \(\frac{1}{3}:3x=\frac{-21}{4}\)

<=> \(3x=\frac{-4}{63}\)

<=> \(x=\frac{4}{189}\)

\(\frac{4}{5}.x=\frac{8}{35}\)

<=> \(x=\frac{2}{7}\)

\(\frac{2}{3x}-\frac{1}{4}=\frac{7}{1}\)

<=> \(\frac{2}{3x}=\frac{29}{4}\)

=> \(8=87x\)

<=> \(x=\frac{8}{87}\)

\(\frac{3}{5x}+\frac{1}{2}=\frac{1}{7}\)

<=> \(\frac{3}{5x}=\frac{-5}{14}\)

<=> \(-25x=42\)

<=> \(x=\frac{-42}{25}\)

\(1-\left(5\frac{3}{8}+x-7\frac{5}{24}\right):\left(-16.\frac{2}{3}\right)=0\)

<=> \(1-\left(\frac{43}{8}+x-\frac{173}{24}\right):\frac{-32}{3}=0\)

<=> \(\frac{43}{8}+x-\frac{173}{24}=\frac{-32}{3}\)

<=> \(\frac{43}{8}+x=\frac{-83}{24}\)

<=> \(x=\frac{-53}{6}\)

học tốt

20) -5-(x + 3) = 2 - 5x ⇔ -5 - x - 3 = 2 -5x ⇔ 4x = 10 ⇔ x = \(\frac{5}{2}\)

Vậy...

1) 16 - 8x = 0 ⇔ 8(2 - x) = 0⇔ 2 - x = 0 ⇔ x = 2

Vậy phương trình có nghiệm là x = 2

b: \(=\left(x^2+3x+1-3x+1\right)^2=\left(x^2+2\right)^2\)

1: Ta có: 7x+6(3-x)=27-20+73

\(\Leftrightarrow7x+18-6x=80\)

\(\Leftrightarrow x=80-18=62\)

Vậy: x=62

2: Ta có: \(6x-5\left(x-7\right)=\left(27-514\right)-486-73\)

\(\Leftrightarrow6x-5x+35=27-514-486-73\)

\(\Leftrightarrow x+35=-1046\)

\(\Leftrightarrow x=-1081\)

Vậy: x=-1081

\(\left(x+2\right)-2=0\)

\(\Rightarrow x+2-2=0\)

\(\Rightarrow x=0\)

\(\left(x+3\right)+1=7\)

\(\Rightarrow x+3+1=7\)

\(\Rightarrow x+4=7\)

\(\Rightarrow x=3\)

\(\left(3x-4\right)+4=12\)
\(\Rightarrow3x-4+4=12\)

\(\Rightarrow3x=12\)

\(\Rightarrow x=4\)

\(\left(5x+4\right)-1=13\)

\(\Rightarrow5x+4-1=13\)

\(\Rightarrow5x+3=13\)

\(\Rightarrow5x=10\)

\(\Rightarrow x=2\)

\(\left(4x-8\right)-3=5\)

\(\Rightarrow4x-8-3=5\)

\(\Rightarrow4x-11=5\)

\(\Rightarrow4x=16\)

\(\Rightarrow x=4\)

\(8-\left(2x+4\right)=2\)

\(\Rightarrow8-2x-4=2\)

\(\Rightarrow4-2x=2\)

\(\Rightarrow2x=2\)

\(\Rightarrow x=1\)

\(7+\left(5x+2\right)=14\)

\(\Rightarrow7+5x+2=14\)

\(\Rightarrow9+5x=14\)

\(\Rightarrow5x=5\)

\(\Rightarrow x=1\)

\(5-\left(3x-11\right)=1\)

\(\Rightarrow5-3x+11=1\)

\(\Rightarrow16-3x=1\)

\(\Rightarrow3x=15\)

\(\Rightarrow x=5\)

1) Ta có: \(\dfrac{3x+7}{11}=\dfrac{5x-7}{9}\)

\(\Leftrightarrow9\left(3x+7\right)=11\left(5x-7\right)\)

\(\Leftrightarrow27x+63=55x-77\)

\(\Leftrightarrow27x-55x=-77-63\)

\(\Leftrightarrow-28x=-140\)

hay x=5

Vậy: S={5}

1, 3x+7/11= 5x-7/9

3x-5x=-7/11-7/9

-2x=-140/99

x= 70/99

vậy ...

2, x-7/4=9/-7+x

x-x=7/4-9/7

x không có gt thỏa mãn 

3, x-1/-2=8/1-x 

x+x =-1/2+8/1 

2x =15/2 

x =15/4 

vậy ...