The distance between the origin and the point nearest to it on the surface $$\,\,{z^2} = 1 + xy\,\,$$ is

If three coins are tossed simultaneously, the probability of getting at least one head is

The standard deviation of a uniformly distributed random variable $$b/w$$ $$0$$ and $$1$$ is

The solution of $$x{{dy} \over {dx}} + y = {x^4}$$ with condition $$y\left( 1 \right) = {6 \over 5}$$