Question

Tìm x trong tỉ lệ thức sau:

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

Trình bày giúp nha, ai nhanh mik T, cần gấp lắm

 

Answer 1

Ta có :\(\frac{\text{3x + 2}}{\text{5x + 7}}=\frac{\text{3x -1}}{\text{5x +1}}\)

=> ( 5x + 1 ) . ( 3x + 2 ) = ( 3x - 1 ) . ( 5x + 7 )

=> 5x(3x + 2 ) + ( 3x + 2 ) = 3x(5x + 7 ) - ( 5x + 7 )

=> ( 15x² + 10x ) + ( 3x + 2 ) = ( 15x² + 21x ) - ( 5x + 7 )

=> ( 3x + 2 ) + ( 5x + 7 ) = ( 15x² + 21x ) - ( 15x² + 10x )

=> ( 3x + 5x ) + ( 2 + 7 ) = ( 15x² - 15x² ) + ( 21x - 10x )

=> 8x + 9 = 11x

=> 9 = 11x - 8x

=> 9 = 3x

=> x = 3

Vậy x = 3

~~Học tốt~~

Answer 2

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

=>       \(\frac{3x+2}{5x+7}\)=\(\frac{1}{2}\)=> ( 3x + 2 ) . 2 = 5x + 7 . 1 => 6x + 4 = 5x + 7 => x=3