S = π r2 = π<span> 11</span>2 = 121 π<span> ≈ 380</span>
2011-11x-220=10x-2010;
2011+2010-220=10x+11x;
3801=21x;
x=181;
S={189}
4:11=12:33 33:11=12:4 4:12=11:33 33:12=11:4
17:5=51:15 15:5=51:17 17:51=5:15 15:51=5:17
6(x-1)²+2(x³-1)-2(x+1)³=26
6x²-12x+6+2x³-2-2x³-6x²-6x-2-26=0
-18x=24
x=-4/3
1.2n+n=1-1, 2.2n=0, n=0/2.2, n=0