Question

Tìm x, biết

1) \(\frac{x-1}{x-5}=\frac{6}{7}\)      2) \(\frac{x-1}{3}=\frac{x+3}{5}\)

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

5) \(\frac{2x+3}{6}=\frac{7x-3}{15}\)

6) \(\frac{6x-5}{-7}=\frac{5x-3}{-5}\)

Answer 1

1) \(\frac{x-1}{x-5}=\frac{6}{7};\left(x-1\right).7=\left(x-5\right).6\)

7x - 7 = 6x - 30 

=> 7x - 6x = -30 - (-7)

x = -23

2) \(\frac{x-1}{3}=\frac{x+3}{5};\left(x-1\right).5=\left(x+3\right).3\)

5x - 5 = 3x + 9

=> 5x - 3x = 9 - (-5)

2x = 14

x = 7

3)  \(\frac{3}{7}=\frac{2x+1}{3x+5};\left(3x+5\right).3=\left(2x+1\right).7\)

9x + 15 = 14x + 7

9x - 14x = 7-15

5x = -8

x = -8/5

Answer 2

1) =>\(\hept{\begin{cases}x-1=6\\x-5=7\end{cases}=>\hept{\begin{cases}x=6+1=7\\x=7+5=13\end{cases}}}\)

Vậy x\(\varepsilon\){7;13}

2)