Question:
$x^{2}-2 a x+\left(a^{2}-b^{2}\right)=0$
Solution:
Given:
$x^{2}-2 a x+\left(a^{2}-b^{2}\right)=0$
On comparing it with $\mathrm{A} x^{2}+B x+C=0$, we get:
$A=1, B=-2 a$ and $C=\left(a^{2}-b^{2}\right)$
Discriminant $D$ is given by:
$D=B^{2}-4 A C$
$=(-2 a)^{2}-4 \times 1 \times\left(a^{2}-b^{2}\right)$
$=4 a^{2}-4 a^{2}+4 b^{2}$
$=4 b^{2}>0$
Hence, the roots of the equation are real.
Roots $\alpha$ and $\beta$ are given by:
$\alpha=\frac{-b+\sqrt{D}}{2 a}=\frac{-(-2 a)+\sqrt{4 b^{2}}}{2 \times 1}=\frac{2 a+2 b}{2}=\frac{2(a+b)}{2}=(a+b)$
$\beta=\frac{-b-\sqrt{D}}{2 a}=\frac{-(-2 a)-\sqrt{4 b^{2}}}{2 \times 1}=\frac{2 a-2 b}{2}=\frac{2(a-b)}{2}=(a-b)$
Hence, the roots of the equation are $(a+b)$ and $(a-b)$.