<span>6 * х + 5 *(х-2)=3х(х-2)</span>
<span>6x+5x-10=3x²-6x</span>
<span>3x²-17x+10=0</span>
<span>D=289-120=169</span>
<span></span>
<span></span>
<span><span>3*х+8*(х-5)=2х*(х-5)</span></span>
<span><span>3x+8x-40=2x²-10x</span></span>
<span><span>2x²-21x+40=0</span></span>
<span><span>D=441-320=121</span></span>
X-2≠0
x≠2 )))))))))))))))))
180/x =180/(x+8) + 8 ; || :4
45/x =45/(x+8) +2 ;
45(x+8) =45x +2x(x+8) ;
45x +360 =45x +2x(x+8) ;
360 =2x(x+8) ;
180 =x(x+8) ;
x² +8x -180 =0 ;
x₁ = -4 -√(4²+180) =-4 -√196 = -4 -14 = -18 ( не решения задачи) ;
x₂ = -4 +√(4²+180) =10 (км/ч).
ответ: 10 км/ч.