$\text{i) -x⁴-2016=0}$
$\text{⇔x⁴+2016= 0}$
$\text{Mà vì x⁴≥0 nên x⁴+2016≥2016>0}$
$\text{Nên phương trình vô nghiệm}$
$\text{k) 3(x+1)-5x.(x+1)=9}$
$\text{⇔3x+3-5.x²-5x=0}$
$\text{⇔-5.x²-2x+3=0}$
$\text{⇔5.x²+2x-3=0}$
$\text{⇔5.x²+5x-3x-3=0}$
$\text{⇔5x(x+1)-3(x+1)=0}$
$\text{⇔(5x-3).(x+1)=0}$
$\text{⇒\(\left[ \begin{array}{l}x=\frac{5}{3}\\x=-1\end{array} \right.\)}$
$\text{l) 2.(x-3)-4.(5-2x)-3x=0}$
$\text{⇔2x-6-20+8x-3x}$
$\text{⇔7x=26}$
$\text{⇔x=$\frac{26}{7}$ }$
