factorise :-
a) 16 a square b square - 25
Answers
Answered by
0
Rewrite
16
a
2
as
(
4
a
)
2
.
(
4
a
)
2
−
40
a
b
+
25
b
2
Rewrite
25
b
2
as
(
5
b
)
2
.
(
4
a
)
2
−
40
a
b
+
(
5
b
)
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
⋅
(
4
a
)
⋅
(
−
5
b
)
Simplify.
2
a
b
=
−
40
a
b
Factor using the perfect square trinomial rule
a
2
−
2
a
b
+
b
2
=
(
a
−
b
)
2
, where
a
=
4
a
and
b
=
−
5
b
.
(
4
a
−
5
b
)
2
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