Это 12 и 17. 12+17=29
12*17=204
А12= а9 + 3d а12= 11 + 3 * 2 = 11 + 6 =17 a1 = a9 - 8d = 11 - 8 * 2 = 11- 16 = -7 S12 = (a1+ a12) : 2 * 12 =( -7 + 17)^2 *12= 10^2 *12 = 5*12 = 60
(10+2√10)/√10=(10+2√10)/√10 * √10/√10=(10√10+20)/10= =10(√10+2)/10=√10 +2
(x-9)/(x-6√x +9)=(√x-3)(√x+3) /(√x-3)²=(√x+3)/(√x-3)=(√x+3)/(√x-3)