a) \(\frac{x+4}{20}=\frac{5}{x+4}\Leftrightarrow\left(x+4\right)^2=100\Rightarrow x+4=+-10\Leftrightarrow x=-4+-10\)
b) \(\frac{x-1}{x+2}=\frac{x-2}{x+3}\Leftrightarrow\left(x-1\right)\left(x+3\right)=\left(x+2\right)\left(x-2\right)\Leftrightarrow x^2+2x-3=x^2-4\Leftrightarrow2x=-1\Leftrightarrow x=-\frac{1}{2}\)
a)\(\frac{x+4}{20}=\frac{5}{x+4}\)
<=>(x+4)2=20.5
<=>(x+4)2-100=0
<=>(x+4-10)(x+4+10)=0
<=>(x-6)(x+14)=0
<=>x-6=0 hoặc x+14=0
<=>x=6 hoặc x=-14
b)\(\frac{x-1}{x+2}=\frac{x-2}{x+3}\)
<=>(x-1)(x+3)=(x-2)(x+2)
<=>x2+2x-3=x2-4
<=>x2+2x-3-x2+4=0
<=>2x+1=0
<=>2x=-1
<=>x=-1/2
