<span>9x^3-27x^2=0</span>
9x^2(x-3)=0
x=0
x=3
1) a1=–8; a2=–6,5; a3=–5
d=a2–a1=–6,5+8=1,5
a10=a1+9d=–8+13,5=5,5
S10=(2a1+9d)/2 *10=(-16+13,5)/2 *10=
=–12,5
2) b1=16/27; b2=16/9; b3=16/3
q=b2:b1=16/9:16/27=(16*27)/(9*16)=3
b8=b1*q^7=16/27*2187=1296
3) a3+a6=3; a2>a7 на 15
a2–a7=15
a3=a1+2d; a6=a1+5d;
a2=a1+d; a7=a1+6d
a1+2d+a1+5d=3; 2a1+7d=3
a1+d–a1–6d=15;
–5d=15
d=–3
2a1+7*(-3)=3
2a1–21=3
2a1=24
a1=12
a2=a1+d=12–3=9
Cos π(x-1)/3 = 1/2
π(x-1)/3=+-π/3+2πk
x-1=3(+-π/3)+6πk
x-1=+-π+6πk
x=1+-π+6πk
k=0 x=1-π≈1-3.14=-2.14
k=1 6π-π+1 >0
k= -1 -6π+π+1< -2.14
наибольший отрицательный корень 1-π