x
4
+
50
x
2
+
625Rewrite
625
as
25
2
.
u
2
+
50
u
+
25
2
Check the middle term by multiplying
2
a
b
and compare this result with the middle term in the original expression.
2
a
b
=
2
⋅
u
⋅
25
Simplify.
2
a
b
=
50
u
Factor using the perfect square trinomial rule
a
2
+
2
a
b
+
b
2
=
(
a
+
b
)
2
, where
a
=
u
and
b
=
25
.
(
u
+
25
)
2
Replace all occurrences of
u
with
x
2
.
(
x
2
+
25
)
2