Question

2/x=7/21 , x+1/x=3/2 , 5/x+1=4/7

Answer 1

2/x=7/21   /na krzyż

7x=42

x=6

 

x+1/x=3/2    /*2

2+2/x=3   /*x

2x+2=3x   /-3x

-x+2=0   /-2

-x=-2   /*(-1)

x=2

 

 

 

 

5/x+1=4/7    /na krzyż

4(x+1)=35

4x+4=35   /-4

4x=31   /:4

x=31/4

x=7 i 3/4

x=7,75

 

Answer 2

2/x=7/21 

 2* 21 = 7*x

 42 = 7x  /:7

 x = 6

x+1/x=3/2 

 2(x+1) = 3x

 2x+2 = 3x

 2x-3x = -2

 -x = -2  /:(-1)

  x = 2

5/x+1=4/7

 4(x+1)=7*5

 4x+4  = 35

 4x = 31   /:4

  x = 31/4

  x = 7  3/4