8000км умножить на 1000 = 8000000
3,1x-1,8x=-40,2+0,55
1,3x=-39,65
x=-30,5
50 + 4 *х = 82
4х = 82 - 50
4х = 32
х = 32 : 4
х= 8
==============
50 + 4 * 8 = 82
50 + 32 = 82
82 = 82
<em>(√(ху)-х)/(√(ху)-х)=</em><em>1</em>
<em>(25х-у)/(5√(ху)+у)=((5√х-√у)(5√х+√у))/(√у(5√х+√у))=(5√х-√у)/(√у)=</em>
<em>=(√у(5√х-√у))/у=</em><em>(5√(ху)-у)/у</em>
<em>можно и так (25х-у)/(5√(ху)+у)=(25х-у)(5√(ху)-у)/((5√(ху)+у)(5√(ху)-у))=</em>
<em>(25х-у)(5√(ху)-у)/(25ху-у²)=(25х-у)(5√(ху)-у)/((25х-у)*у)=</em><em>(5√(ху)-у)/у</em>