A₁=3*1+5=8
A₂=6+5=11
d=A₂-A₁=11-8=3
A₃₀=A₁+d*29=8+29*3=95
A₄₀=A₁+d(n-1)=8+3*39=125
S₁₁=(11(95+125))/2=1210
(a+2)*96 / 2(a-4)*a(a+2)=
=48/a(a-4)
(3a/a-4) - (48/a(a-4) =
=(3a²-48)/a(a-4) =
= 3(a²-16)/a(a-4) =
= 3(a-4)(a+4) /a(a-4) =
=3(a+4)/a
1)-4a+3b-2a+7b=-6a+10b
2)0,3x-2(0,7+0,5y)+1/10x=0,3x-1,4-1y+1/10x=0.4x-1,4-1y
(160-20p)*p=300
160p - 20p^2 - 300=0
-p^2+80p-150=0
D=6400-6000=400
p1=30
p2=50
Ответ: р=50