1
WB JEE 2008
+1
-0.25

If a, b, c be in Arithmetic progression, then the value of $$(a + 2b - c)(2b + c - a)(a + 2b + c)$$ is

A
16 abc
B
4 abc
C
8 abc
D
3 abc
2
WB JEE 2008
+1
-0.25

If three real numbers a, b, c are in Harmonic Progression, then which of the following is true?

A
$${1 \over a},b,{1 \over c}$$ are in A.P.
B
$${1 \over {bc}},{1 \over {ca}},{1 \over {ab}}$$ are in H.P.
C
ab, bc, ca are in H.P.
D
$${a \over b},{b \over c},{c \over a}$$ are in H.P.
3
WB JEE 2008
+1
-0.25

The sum of the infinite series $${\left( {{1 \over 3}} \right)^2} + {1 \over 3}{\left( {{1 \over 3}} \right)^4} + {1 \over 5}{\left( {{1 \over 3}} \right)^6} + ...$$ is

A
$${1 \over 4}{\log _e}2$$
B
$${1 \over 2}{\log _e}2$$
C
$${1 \over 6}{\log _e}2$$
D
$${1 \over 4}{\log _e}{3 \over 2}$$
4
WB JEE 2009
+1
-0.25

If a, b, c are G.P. (a > 1, b > 1, c > 1), then for any real number x (with x > 0, x $$\ne$$ 1) logax, logbx, logcx are in

A
G.P.
B
A.P.
C
H.P.
D
G.P. but not in H.P.
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