Judge whether the following functions are quadratic functions. If they are quadratic functions, please state their quadratic coefficients, primary coefficients and constant terms （1）y=2x²-3； （2）y=3x-1； （3）y=（2x-1）（1-x）； （4）y=1/x²+1.

Judge whether the following functions are quadratic functions. If they are quadratic functions, please state their quadratic coefficients, primary coefficients and constant terms （1）y=2x²-3； （2）y=3x-1； （3）y=（2x-1）（1-x）； （4）y=1/x²+1.

(1) Y = 2x & sup2; - 3 the coefficient of quadratic term of quadratic function is 2
The coefficient of the first term is 0 and the constant term is - 3
(2) Y = 3x-1 is not a quadratic function
(3) Y = (2x-1) (1-x) is a quadratic function, the coefficient of quadratic term is - 2, the coefficient of quadratic term is 3, and the constant term is - 1
(4) Y = 1 / X & sup2; + 1 is not a quadratic function