Question:
The number of real solutions of $\left|2 x-x^{2}-3\right|=1$ is
(a) 0
(b) 2
(c) 3
(d) 4
Solution:
(b) 2
Given equation: $\left|2 x-x^{2}-3\right|=1$
(i) $2 x-x^{2}-3=1$
$\Rightarrow 2 x-x^{2}-4=0$
$\Rightarrow x^{2}-2 x+4=0$
$\Rightarrow(x-2)^{2}=0$
$\Rightarrow x=2,2$
(ii) $-2 x+x^{2}+3=1$
$\Rightarrow x^{2}-2 x+2=0$
$\Rightarrow x^{2}-2 x+1+1=0$
$\Rightarrow(x-1)^{2}-i^{2}=0$
$\Rightarrow(x-1+i)(x-1-i)=0$
$\Rightarrow x=1-i, 1+i$
Hence, the real solutions are 2,2 .