∴a+b=2.
When x = 0 and 1,-1≤c≤ 1,-1≤a+b+c≤ 1,
Therefore,-1≤ c = (a+b+c)-2 ≤1-2 =-1,
∴c=- 1.
When x = 0, y 1 =- 1 is the minimum value of the function y 1 on x ∈ [- 1, 1].
Therefore, x = 0 is the symmetry axis of the function y 1
That is -b/2a = 0, b = 0 and a = 2.
That is, y 1 = 2x 2- 1, y2 = 2x.
The coordinates of the intersection of the two are
A(( 1-√3)/2， 1-√3)、B(( 1+√3)/2， 1+√3)。
Since the integer solution of (1-√ 3)/2 ≤ x ≤ (1+√ 3)/2 is x = 0,1.
The corresponding grid is
O (0，0)，M(0，- 1)，N ( 1， 1)，P ( 1，2)。
∴ Quadrilateral OMNP happens to be a parallelogram,
Its area is: S = 1× 1 = 1.