A.
radicand or determinant is if have equation
ax^2+bx+c=0
determinant is

if

>0, then you have 2 real roots
if

=0, then you ahve 1 real root
if

<0, then you ahve 2 complex roots
9x^2-36+36
a=9b
b=-36
c=36


we can see that they cancel out and therefor

=0
there is 1 real root
B. factor
(2x-7)(x-1)=0
set each to zero
2x-7=0
2x=7
x=7/2
x-1=0
x=1
x=7/2 and 1