Chapter II Quadratic Function (Volume II)

1~5DBACC 6~ 10DDDCC

1 1, upward straight line x =- 1 (- 1, -5) 12, y = (x-2) 2- 1 etc. -1 16, y = y = x 217, (2)(3)(4) 18, all curves are symmetrical, parabola has the maximum value, hyperbola has no intersection with coordinate axis, 1 (0

2 1, image omitted, x= 1, y= 1 22. (1) From the image, we know that the equation x 2-2x-3 = 0 and get the solution x 1 = 3, x2 =- 1 (. = 1 or x>3, and the function value is greater than 0 (3)- 1

23.Y =-2x 2+4x-5224, ∵PA⊥x axis, and the ordinate of point ap= 1∴p is 1. When y= 1, 3/4x2-3/2xx2 =1-radical number 2, the symmetry axis of the ∵ parabola is x= 1, the point p is on the right side of the symmetry axis, and ∴x= 1+ radical number 2. So yn =-3/50× 5 2+6 = 4.5, so the column length MN is 10-4.5=5.5 m (3) Let DE be the width of the isolation belt and EG be the sum of the widths of three cars, then the coordinate of G point is (7,0) (7 = 2 ÷ 2+2. According to the characteristics of parabola, we can know that three cars can drive side by side in one lane. The expression of the quadratic function that meets the requirements is: y =1/3(x- 1)2-1,y = root number 3 (x-1) 2-root number 3.