Question

Tìm x thuộc N biết : 

 x : 2 - 4 = 3 

( x + 1 ) : x = 2 

5 ( x - 3 ) - 4 ( x - 1 ) = 20

Answer 1

\(x:2-4=3\)

\(x:2=3+4\)

\(x:2=7\)

\(x=7\cdot2\)

\(x=14\)

\(\left(x+1\right):x=2\)

\(x+1=2x\)

\(x=1\)

\(5\left(x-3\right)-4\left(x-1\right)=20\)

\(2x-15-4x+4=20\)

\(2x-4x=20+15-4\)

\(-2x=31\)

\(x=31:\left(-2\right)\)

\(x=-\frac{31}{2}\)

Answer 2

x : 2 - 4 = 3

=> x : 2 = 7

=> x = 3,5

vậy_

(x + 1) : x = 2

=> x : x + 1 : x = 2

=> 1 + 1 : x = 2

=> 1 : x = 1

=> x = 1

vậy_

5(x - 3) - 4(x - 1) = 20

=> 5x - 15 - 4x + 4 = 20

=> 1x = 31

=> x = 31

vậy_