Equating coefficients we see that ......
Equating the coefficient of $x^2$ in $V$ to zero, we get ......
Now equate the coefficients of $x^2$ at either end of this chain of equalities.
Go to the list of words starting with: a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
p
q
r
s
t
u
v
w
y
z