x+y+cosy=0 x'+y'+(cosy)'=0' 1+y'-siny*y'=0 (siny-1)y'=1 y'=1/(siny-1) y"=-(siny-1)'/(siny-1)^2 =-cosy*y'/(siny-1)^2 =-cosy*(1/(siny-1))/(siny-1)^2 =-cosy/(siny-1)^3
