The utility function of Vivian is given by u(x1, x2 ) = 2x1x2 + 3. The income is m and the prices(positive) are p1 and p2, respectively.

1. Derive ordinary demand functions for both goods.
2. Are these two good substitutes or complements? Why?
3. Is x1 a normal good or an inferior good? Is it a luxury or necessary good? Is it an ordinary or inferior good? Justify your answers.

(Please explain a little more detail, thank you!)