a)
<=>3−4x(25−2x)=8x^2+x−300
<=>3−100x+8x^2=8x^2+x−300
<=>8x^2−100x+3=8x^2+x−300
<=>−101x=−300−3
<=> x = 3
b) $\frac{(x+2)x}{(x-2)x}$- $\frac{x-2}{x(x-2)}$= $\frac{2}{x(x-2)}$
<=> $x^{2}$ +2x -x-2=2
<=> $x^{2}$ +x−4=0
<=> (x+$\frac{1}{2}$ )^2−4−($\frac{1}{2}$ )^2=0
<=> x + $\frac{1}{2}$ = + - $\sqrt{\frac{17}{4}}$
<=> x = $\frac{-1+\sqrt{17}}{2}$
<=> x = $\frac{-1-\sqrt{17}}{2}$