Ответы и объяснения

2014-03-31T21:42:24+04:00
1/2x+1/6x+1/12x+1/20x+1/30+1/42x=-6
1/2x+1/6x+1/12x=(6+2+1)/12x=9/12x
9/12x+1/20x+1/30x=(45+3+2)/60x=50/60x
50/60x+1/42x=(350+10)/420x=360/420x=6/7x
6/7x=-6
x=-6*7/6
x=-7