Х-18-42 = Х - 60 ПРИ Х=70, 70-60= 10
(√(43)-1)² = 43-2√(43)+1 = 44-2√(43).
A1=8 a2=11 d=11-8=3
S(30-40)=S(40)-S(29)=(16+3*39)*40/2 - (16+3*28)*29/2=(16+117)*20 - (16+84)*29/2=
=133*20 - 50*29=2660-1450=1210
10!=1*2*3*4*5*6*7*8*9*10=3628800
10!*5!=3628800*120=435456000