True or False:

1) The quadratic form Q(x,y)= 7x²-16y² admits an improper isometry

2) Let p be an odd prime. The Legendre symbol (p7 )is determined by the congruence class of p mod 7

3) The equation 7x³+12=y³ has no integer solutions

4) Let Q be a binary quadratic form whose range topograph has a lake. Then Q factors as a product of two linear forms with integer coefficients.