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Mathematics
Problem
The decimal logarithms (base
10
10
10
) of three positive numbers
x
x
x
,
y
y
y
, and
z
z
z
are in arithmetic progression. If
y
=
15
y=15
y
=
15
and
x
+
z
=
45
x+z=45
x
+
z
=
45
, find the common ratio
r
>
1
r>1
r
>
1
of the geometric progression formed by
x
x
x
,
y
y
y
, and
z
z
z
. a)
3
\sqrt3
3
b)
3
+
5
2
\dfrac{3+\sqrt5}{2}
2
3
+
5
c)
3
3
3
d)
1
+
5
2
\dfrac{1+\sqrt5}{2}
2
1
+
5
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