@ @¶ìÿa@óÝy‹¾a@ u@ @YV x = 12 ± −16 . 2 . .255 ( ) . x +2 .x x(x + 2) = 255 x 2 + 2x − 255 = 0 (x + 17)(x − 15) = 0 .x = 15 x = −17 .17 15 −15 −17 ABCD () () . BCXY ADXY x AB . AB . ABCD AD .1+ 5 1 AD 2