The number of real roots of the equation $x|x|-5|x+2|+6=0$, is :
Solution
$$
\begin{aligned}
& x|x|-5|x+2|+6=0 \\\\
& \text { Case-I : } \\\\
& \text { When } x<-2 \text { then } \\\\
& -x^2+5(x+2)+6=0 \\\\
& \Rightarrow x^2-5 x-16=0 \\\\
& \Rightarrow x=\frac{5 \pm \sqrt{25+64}}{2} \\\\
& \therefore x=\frac{5-\sqrt{89}}{2} \text { is accepted }
\end{aligned}
$$
<br/><br/><b>Case-II :</b>
<br/><br/>$$
\begin{aligned}
& \text { When } -2 \leq x < 0 \text { then } \\\\
& -x^2-5(x+2)+6=0 \\\\
\Rightarrow & x^2+5 x+4=0 \\\\
\Rightarrow & (x+1)(x+4)=0 \\\\
& x=-1 \text { is accepted }
\end{aligned}
$$
<br/><br/><b>Case-III :</b>
<br/><br/>$$
\begin{aligned}
& \text { When } x \geq 0 \text { then } \\\\
& x^2-5(x+2)+6=0 \\\\
\Rightarrow & x^2-5 x-4=0 \\\\
& x=\frac{5 \pm \sqrt{25+16}}{2} \\\\
& =\frac{5 \pm \sqrt{41}}{2} \\\\
& x=\frac{5 - \sqrt{41}}{2} \text { is accepted } \\\\
\therefore & 3 \text { real roots are possible. }
\end{aligned}
$$
About this question
Subject: Mathematics · Chapter: Complex Numbers and Quadratic Equations · Topic: Complex Numbers and Argand Plane
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