3х(1-2х)(2х+1)=3х-12x³
3х(1-2х)(2х+1)=(3x-6x²)*(2x+1)=
=6x²+3x-12x³-6x²= 3x-12x³
3x-12x³=<span>3x-12x³
</span>
Ч.т.д
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ордината - это у, равна 0
значит
12х-15*0=132
12х=132
х=132/12
x=11
1. S8=5/32; q=–0,5
S8=b1*(q^8–1)/(q–1)=b1*(-255/256)/(–1,5)=b1*(-255*2/256*(-3)=b1*(510/768)
b1*(510/768)=5/32
b1=(5*768)/(32*510)=24/102=12/51
2. y1=0,55; y2=0,44
q=y2/y1=0,44/0,55=0,8
S4=y1*(q^4–1)/(q–1)=0,55*(-0,5904)/(-0,2)=1,6236