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UPSC CDS Math Basic operation and Factorisation Questions
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© examsnet.com
Question : 29
Total: 77
If
a
2
−
1
a
=
5
,then what is the value of
a
6
−
1
a
3
?
[2018 CDS-I]
125
−
125
140
−
140
Validate
Solution:
Here,
a
2
−
1
a
=
5
⇒
a
−
1
5
=
5
and
a
5
−
1
a
3
or
a
3
−
1
a
3
=
?
a
3
−
1
a
3
=
(
a
−
1
a
)
3
+
3
(
a
−
1
a
)
=
5
3
+
3
(
5
)
=
125
+
15
=
140
© examsnet.com
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