1. Known parabola y=ax? 0? If the coefficient of 5+bx+c is a-b+c=0, then this parabola passes through point _ _ _ _ 2. Parabola y=ax? 0? The opening of 5+bx+c is downward and intersects with X axis at point A (-3.0), the symmetry axis is straight line x=- 1, and the distance from vertex C to X axis is 2. Find the analytical expression of this parabola. 3. Known parabola y=x? 0? 5-5mx+4m？ 0? 5(m is a constant) ① Verification: This parabola must intersect with the X axis ② Is there a positive number m, so that the distance between the two intersections of the parabola and the X axis is known to be equal to 6/m- 1, (6 is a molecule)? If it exists, find the value of m; If it does not exist, please explain why. 4. Known parabola y=mx? 0? 5+(3-2m)x+m-2(m≠0) has two different intersections with the X axis. ① Find the value range of m; Answer, 1. (-1,0) 2.A (- 1, 2) B (-3.0) C (1.0) brings y=ax? 0? A =-0.5b =-1c = 65438+5+0.5 of bx+c, that is, y=-0.5x? 0? 5-x+ 1.53。 Prove y=x? 0? 5-5mx+4m？ 0? If 5 is always greater than 0, you can pull the second question. I summed up a formula, that is, the square of B minus 4ac under the root sign, and then divide this by the absolute value of A, which is the length between AB. Remember that this formula is not equal to 1.5.