-0,1x(2x^2+6)(5-4x^2)=(-0,2x^3-0,6x)(5-4x^2)=-1x^3+0 ,8x^5-3x+2,4 x^3=1,4x^3 +0,8x^5-3x
A1=2
d=3
a6=a1+5*d=2+15=17
s6= ((a1+a6)*6) / (2) = (12+102)/2=57
Сosacosb-sinasinb=cos(a+b)
cos24cos31-sin2xsin31=cos(24+31)=cos55
-24m^2-24n-16m-36mn=(-24m^2-16m)+(-24n-36mn)= -8m(3m+2)-12n(3m+2)= (3m+2)(-8m-12n)