Please help me with this quadratics question Thanks so much

Please help me with this quadratics question. Thanks so much!

Consider two different quadratic functions of the form f (x) = 4x^2 25. The graph of each function has its vertex on the x-axis. Find both values of q. For the greater value of q. solve f(x) = 0. Find the coordinates of the point of intersection of the two graphs.

Solution

Given, 4x^2 - qx + 25
(a)weknow that (2x +5)(2x+5) are the positive roots that will form 4x^2+20x+25, and (2x-5)(2x-5) are the negative roots that will form 4x^2 -20x + 25
so q can be -20 or + 20.

(b) As 20 is the greater value however 4x^2 - qx + 2 will make 4x^2 -20x + 25 the function when q= 20 (as it is -q not +q)
f(x) = (2x -5)*(2x-5) = 0
=> 2x -5 = 0
=> 2x = 5
=> x = 5/2
f(5/2) = 0

(c) 4x^2 - 20x + 25 = 4x^2 + 20x + 25
=> -40x = 0
=> x = 0
so, f(0) = (2*0 +5)*(2*0+5)
=> f(0) = 5 * 5
=> f(0) = 25