Tìm x để (x - 9).B < 2x

cho A=√x / √x+1 ; B=5√x-9 / x-5√x+6 + √+2 / 3-√x + √x-1 / √x-2 (x ≥0 ; khac 9)
a, tinh A khi x=1
b, rut gon B
c, tim x de (x-9).B<2x