A6=a1+5d;a1=a6-5d; a1=-147-15=-162 an=a1+(n-1)*d; an>0;
<span>a1+(n-1)*d>0; </span>
<span>-162+3n-3>0; </span>
<span>3n>165; </span>
<span>n>55 то есть при n=56</span>
А)12m^2-3m= 3m(4m-1)
b)3x-6y+xy-2y^2=(3x+xy)-(6y+2y^2)=x(3+y)-2y(3+y)=(x-2y)×(3+y)
в) 4n^2-9 = (2n-3)×(2n+3)
г)k^3-8k^2+16k= k(k^2-8k+16)=k× (k-4)^2