25704 : 306 = 84
4236 + 84 = 4320
6049 - 385 = 5664
5664 * 5400 = 30585600 (Ват?!?)
30585600 : 4320 = 7080
F'(x)=((x²+x+1)/(x²+1))'=[(x²+x+1)' *(x²+1)-(x²+1)' *(x²+x+1)] / [(x²+1)²]=
=[(2x+1)*(x²+1)-2x*(x²+x+1)] / [(x²+1)²]=[2x³+x²+2x+1-2x³-2x²-2x] / [(x²+1)²]=[-x²+1]/[(x²+1)²]