Question

Решить lg(7x)-lg(5x+1)=0

Answer 1

Объяснение:

потом 7x-5x=1

2x=1

x=1/2 или 0.5

Answer 2

$\displaystyle\bf\\\lg(7x)-\lg(5x+1)=0\\\\ODZ:\\\left \{ {{x>0} \atop {5x+1>0}} \right. \\\\\\\left \{ {{x>0} \atop {x>-0,2}} \right. \ \Rightarrow \ \ x>0\\\\\\\lg\frac{7x}{5x+1}=0\\\\\\\frac{7x}{5x+1} =1\\\\\\\frac{7x}{5x+1} -1=0\\\\\\\frac{7x-5x-1}{5x+1} =0\\\\\\\left \{ {{2x-1=0} \atop {5x+1\neq 0}} \right. \\\\\\\left \{ {{x=0,5} \atop {x\neq -0,2}} \right.\\\\\\Otvet:0,5$