3=4a+2b+c (2)

- 12=9a-3b+c (3)

(2)-( 1) - 1=3a+b

(3)-(2) - 15=5a-5b -3=a-b

Addition 4a=-4 a=- 1 b=2 c=3.

y=-x^2+2x+3

2.y=a(x- 1)(x+5) Vertex abscissa x=2.

x=2 y=7a=9/2 a=9/ 14

y=9/ 14(x- 1)(x+5)

3. Through point A(0, -3), c=-3.

Pass through point B(2, -3) -3=4a+2b-3 2a+b=0.

Passing point C(- 1, 0) 0=a-b-3 a-b=3.

a= 1 b=-2 c=-3

y=x^2-2x-3

4. What is the relationship between the parabolas passing through points (0,2), (-1,-1) with the Y axis as the symmetry axis?

y=-3x^2+2

5. If the image of quadratic function y = x+bx+c passes through points (1, -2), (-1, 6), what is the relationship of this quadratic function?

-2= 1+b+c

6= 1-b+c

c= 1 b=-4

y=x^2-4x+ 1