=√d(√d-8)/(√d-8)(√d+8)=√d/√d+8
<span>x^3-64x=0
x^3=64x
x=8
Проверка:
8^3=64*8
512=512</span>
9/(1-b)² * (b²-1)/9 = 9/(b-1)² * (b-1)(b+1)/9 = (b+1)/!b-1!
A2+a5 = 8
a3+a7 = 14
a1+d+a1+4d = 8
a1+2d +a1+6d = 14
2a1+5d = 8
2a1+8d = 14
3d = 6
d = 2
2a1+5*2 = 8
2a1 = -2
a1 = -1