y = 4000200-m00000001+162800000m+4000000000005+00000000000150+50m^-05^2m^05+4000m-m^0500000001+000000019+42^059m;求上述式子y的极值

为了求出y的极值，我们需要对y求导数并令其等于0。

对第一项求导：

y1 = 4000*(200-m)(0.0000001+1/(62800000m))

y1' = 4000*(-1)(0.0000001+1/(62800000m)) + 4000*(200-m)(-1/(62800000m^2))

对第二项求导：

y2 = 4000*(0.00000005+0.00000000001*(50+50*m^(-0.5))^2)*m^(0.5)

y2' = 4000*(0.00000000001)(50+50m^(-0.5))(1/2)m^(-0.5) + 4000(0.00000000001)(50+50m^(-0.5))^2(1/2)m^(-1/2) + 4000(0.00000005+0.00000000001*(50+50m^(-0.5))^2)(1/2)*m^(-1/2)

对第三项求导：

y3 = 4000*(m-m^(0.5))(0.0000001+0.0000001(9+42^0.5)/(9m))

y3' = 4000*(1-(1/2)m^(-0.5))(0.0000001+0.0000001*(9+42^0.5)/(9m)) - 4000*(m-m^(0.5))(0.0000001+0.0000001(9+42^0.5)/(9m^2))

将y1'、y2'、y3'都等于0，解出m的值，代入y的式子中即可得到y的极值。