Đáp án:
$a) x=\dfrac{3}{5}$
$b){\left\{\begin{aligned}x=1\\y=-2\end{aligned}\right.}\\$
Giải thích các bước giải:
$a) 5x^3-3x^2+10x-6=0\\
\Leftrightarrow x^2(5x-3)+2(5x-3)=0\\
\Leftrightarrow (5x-3)(x^2+2)=0\\
\Leftrightarrow {\left[\begin{aligned}5x-3=0\\x^2+2=0 (LV)\end{aligned}\right.}\\
\Leftrightarrow x=\dfrac{3}{5}$
Vì $x^2>0\Rightarrow x^2=2>0$
$b) x^2+y^2-2x+4y+5=0\\
\Leftrightarrow x^2-2x+1+y^2-4y+2^2=0\\
\Leftrightarrow (x-1)^2+(y-2)^2=0\\
\Rightarrow {\left\{\begin{aligned}x-1=0\\y+2=0\end{aligned}\right.}\\
\Rightarrow {\left\{\begin{aligned}x=1\\y=-2\end{aligned}\right.}\\$
