What is 2,789 rouned to the neatest yen

Which graph represents the equation y =4x

Why can't my rank go i have 1723 points, but my rank is only at ambitious, which is only 250 points! like, (p.s. i know this isn't related to math, but i just don't know why it's doing this and i would really appreciate if someone could tell me whats going on with this)

Let f of x equals the integral from 1 to 3 times x of the natural logarithm of t squared. use your calculator to find f″(1).