y²=2px
取x轴上部作函数
y
=√(2px)
=(2px)^(1/2)
得
y'
=(1/2)*(2px)^(-1/2)*(2px)'
=(1/2)*[1/√(2px)]*2p
=p/√(2px)
=√(p/2x)
y2=2px
y=+/- sqrt(2px)
y=+/- sqrt(2p)sqrt(x)
y' = +/- sqrt(2p)(1/2)x^(-1/2)
y' = +/- sqrt(2p)/2sqrt(x)
y'^2 = p/2x (........)
y2=2px
2yy'=2p
y'=2p/2y=p/y=p/2px=1/2x
y^2=2px
2yy'=2p
y'=2p/2y=p/y=p/2px=1/2x
y=4px