x2−px+45p=0
For rational roots, D must be a perfect square.
D=p2−5p=p(p−5)
Now put values in reverse order as q is the maximum value of p
At p=10,
D=50→not a perfect square
At p=9,
D=36→perfect square
So, the maximum integral value of p is 9
∴q=9
0≤y≤(x−9)2

Area of shaded region =∫09(x−9)2dx
=[3(x−9)3]09=243unit2