Let the equation of circle be

Put   x = 0

            ⇒         y² + $\mathrm{\lambda }$y + 9 = 0

            $\therefore$         | y¹ – y² | = $2\sqrt{7}$

            ⇒         ($\mathrm{\lambda }$)² – 36 = 28    ⇒        ${\mathrm{\lambda }}^2$ = 64             ⇒         $\mathrm{\lambda }$ = ± 8

            So, equation of circles is x² + y² – 6x ± 8y + 9 = 0

            Similarly, equation of other circle will be

                        x² + y² + 6x ± 8y + 9 = 0.