Answer:
quadratic equation is 2 degree polynomial
x2 - x -72 = x2 - 9x +8x -72
x(x - 9 ) + 8(x - 9) = (x -9) (x+8)
1st correct - quadratic
2nd correct - quadratic
3rd - it's linear equation, not quadratic
4th - correct - quadratic
5th - linear - not correct