1/3,1/4,1/5,1/6,1/7,1/8,1/9,2/5,2/7,2/9, 3/7, 3/8, 4/9.
5м=500см
1 м 80 см = 180см
S=500 умножить на 180 =90000см
90000см=900м
(x²+y²)dx-2xydy=0
(1+y²/x²)dx-2(y/x)•dy=0
2(y/x)•y'=(1+y²/x²).
Однородное уравнение.
y=tx; y’=t’x+t;
2t•(t’x+t)=1+t² => 2t•t’x+2t²=1+t²
2t•t’x=1-t²
2t•dt/(1-t²)=dx/x => -INT[1/(1-t²)]d(1-t²)=INTdx/x
ln|1-t²|=-ln|x|+C => 1-t²=C/x => t²=1-C/x.
<span>y²/x²=1-C/x => y²=x²-Cx.</span>