X^2+2x = 63
x^2+2x-63 = 0
D = 4+4*63 = 256 = (16)^2
x1 = -9, x2 = 7
А) 4/15+9/10+41/10+11/15=(4/15+11/15)+(9/10+41/10)=15/15+50/10=1+5=6
б)17/16+12/13+15/16+14/13=(17/16+15/16)+(12/13+14/13)=32/16+26/13=2+2
в) 5/8+7/18+3/8+11/18+1/8=(5/8+3/8+1/8)+(7/18+11/18)=9/8+18/18=1,1/8+1=2,1/8
1 - а
2 - а*2=2а
3 - а+2а=3а
а+2а+3а=6а
а=139
6*139=834