12/(x-2)(x²+2x+4)+(x+1)/(x²+2x+4)=4/(x-2)
x≠2
12+(x+1)(x-2)=4(x²+2x+4)
4x²+8x+16-12-x²+2x-x+2=0
3x²+9x+6=0
x²+3x+2=0
x1+x2=-3 U x1*x2=2
x1=-1 U x2=-2
1.440
2.714018000
3.42030939
6/7:2=6/7 * 1/2 =<u /> 3/7
1/7 : 2 =1/7 * 1/2= 1/14
15/11:5=15/11*1/5=3/11
17/11:5=17/11 * 1/5 =17/55
S = t * v
s = 4 * 83 = 332
ответ: 332 км
4) 19/42+6/7=19/42+6*6/7*6=(19+36)/42=55/42=1+13/42
6) 3/8+1/56=3*7/8*7+1/56=22/56=11/28
2)10/21-1/3=10/21-7/21=3/21=1/7
6)1/3-7/30=10/30-7/30=3/30=1/10