According to the following conditions, the analytic expression of quadratic function is obtained: (1) the image of quadratic function passes through points (1,0), (- 1, - 6), (2,6); A + B + C = 0 - A-B + C = - 6, 4A + 2B + C = 6, add two forms to get C = - 3, then a + B = 3 and 4A + 2B = 9 can get a = 1.5, B = - 4.5

According to the following conditions, the analytic expression of quadratic function is obtained: (1) the image of quadratic function passes through points (1,0), (- 1, - 6), (2,6); A + B + C = 0 - A-B + C = - 6, 4A + 2B + C = 6, add two forms to get C = - 3, then a + B = 3 and 4A + 2B = 9 can get a = 1.5, B = - 4.5

y=ax^2+bx+c
a+b+c=0
A-B + C = - 6
4a+2b+c=6
The solution is a = 1, B = 3, C = - 4
The analytic expression of quadratic function y = x ^ 2 + 3x - 4

Find the analytic expression of quadratic function according to the condition
1. Parabola passing (- 1,0), (3,0), (1. - 5);
2. The vertex of the parabola is (- 2, - 5) and passes through (1, - 14)

1. Let y = a (x + 1) (x-3) and point (1, - 5) be on it,
-5=a(1+1)(1-3),
a=5/4,
The analytic formula of quadratic function is y = 5 / 4 (x ^ 2-2x-3)
2. Let y = a (x + 2) ^ 2-5, passing through point (1, - 14)
-14=a(1+2)^2-5,
a=-1,
The analytic expression of quadratic function y = - (x + 2) ^ 2-5

General formula: y = ax & # 178; + BX + C
The symbol of C: C is the ordinate of the intersection of the image and the Y axis
Does he mean: when the coordinate is (0, y), C = y? Or when the coordinate is (0, y), the positive and negative sign of C = the positive and negative sign of Y?
Entanglement~

Substituting x = 0
Then y = 0 + 0 + C = C
So when (0, y), y = C