If a = 3+√5 find a^2 + 1/a^2
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Step-by-step explanation:
a=
2
3+
5
∴
a
1
=
3+
5
2
On rationaliging the denominator , we get ,
a
1
=
(3+
5
)(3−
5
)
2(3−
5
)
=
9−5
6−2
5
=
4
6−2
5
=
2
3−
5
Also,
(a+
a
1
)
2
=a
2
+
a
2
1
+2
Substituting the values of a
=
a
1
,
We get ,
`(
2
3+
5
+
2
3−
5
)
2
=(a
2
+
a
2
1
+2)
∴a
2
+
a
2
1
+2=(
2
3+
5
+3−
5
)
2
=(3)
2
=9
∴a
2
+
a
2
1
=9−2=7.
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