An = a1 + d(n-1)
128 = a1 + 4*29
128 = a1 + 116
-a1 = 116 - 128
-a1 = -8|(-1)
a1 = 8
Ответ: 2) 8.
6а³-6а=6а(а²-1)=6а(а-1)(а+1)
5х³-5ху²=5х(х²-у²)=5х(х-у)(х+у)
Bn = 3п - <span>1
b1=3*1-1=2
b2=3*2-1=5
b3=3*3-1=8
..................
b60=3*60-1=179
d=b2-b1=5-2=3
S(60)=(b1+b60):2*60=(2+179):2*60=181*30=5430
</span>
Х²-4х+3=0
D=(-4)²-4*3=16-12=4=2²
x1=(4+2)/2=3
x2=(4-2)/2=1