JEE MAIN - Mathematics (2024 - 5th April Morning Shift - No. 30)
The number of distinct real roots of the equation $$|x||x+2|-5|x+1|-1=0$$ is __________.
Answer
3
Explanation
$$|x| \quad|x+2|-5|x+1|-1=0$$
$$\begin{aligned} & \text { (I) if } x<-2 \\ & x^2+2 x+5 x+5-1=0 \\ & x^2+7 x+4=0 \Rightarrow \text { one root satisfying } x<-2 \end{aligned}$$
$$\begin{aligned} & \text { (II) if }-2 \leq x<-1 \\ & -x^2-2 x+5 x+5-1=0 \\ & x^2-3 x-4=0 \Rightarrow \text { not root satisfying }-2 \leq x<-1 \end{aligned}$$
$$\begin{aligned} & \text { (III) if }-1 \leq x<0 \\ & -x^2-2 x-5 x-5-1=0 \\ & x^2+7 x+6=0 \\ & x=-1 \text { is only root satisfying }-1 \leq x<0 \end{aligned}$$
(IV) if $$x \geq 0$$
$$\begin{aligned} & x^2+2 x-5 x-5-1=0 \\ & x^2-3 x-6=0 \end{aligned}$$
one root satisfying $$x \geq 0$$
$$\Rightarrow$$ The number of distinct real roots are three.
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