b
plot x^6-x^4+y^2+2*y+3/64=0
plot 6.8*exp(-7*x/10)
plot -1/(0.125*PI)*(2-(x*x+y*y)/0.25)*exp(-(x*x+y*y)/0.5)+6
plot exp(-x*x/0.5)-0.3*exp(-x*x/8)
plot 1/(1+exp(-2*x))
plot 1/(1+exp(-x))