Quadratic function 2a-b A > 0, b > 0

Because - B / 2a0
So - B0 (1)
And because B 0 is - 2b > 0 (2)
（1） (2) 2a-b > 0

What is the relationship between the b value of quadratic function and the image of quadratic function?

1. The quadratic function y = ax & # 178; + BX + C (a ≠ 0), because the axis of symmetry is x = - B / (2a), so B and a determine the position of the axis of symmetry together
2. Because the abscissa of vertex is - B / (2a), the ordinate is (4ac-b & # 178;) / (4a), so B and a determine the abscissa of vertex together, B and a, C determine the ordinate of vertex together

If a > 0, B

If a > 0, B0
3b0
So, 2a-3b > 0 is a positive number

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