Which of the following is an acceptable row operation when conducting Gaussian Elimination

How many solutions does the nonlinear system of equations graphed bellow have?

Aword processing program requires a 7- digit registration code made up of the digits 1,2,4,5,6,7 and 9 each number has to be used and no number can be used mor than once how many codes are possible

Find the missing dimension! need asap! tiny square is a =3025 in ²