m2 - 81 = (m-9)(m+9)
b2 - 121c2 = (b- 11c)(b +11c)
169m2 - 16n2 = (13m - 4n)(13m+4n)
36m4 - k2p2 = (6m2-kp)(6m2+kp)
(a+3)2 - 144 = a2 + 6a+9 -144 = a2 +6a -135 D= 36+ 4*135 = 24 x1 = 6-24/2 = -9 x2 = 6+24/2 = 15
2. x2- 289 = 0
(x-17)(x+17)=0
x=17 или x=-17