1
WB JEE 2008
+1
-0.25

The sum of the series $$(1 + 2) + (1 + 2 + {2^2}) + (1 + 2 + {2^2} + {2^3}) + ....$$ upto n terms is

A
$${2^{n + 2}} - n - 4$$
B
$$2({2^n} - 1) - n$$
C
$${2^{n - 1}} - n$$
D
$${2^{n + 1}} - 1$$
2
WB JEE 2008
+1
-0.25

The 5th term of the series $${{10} \over 9},{1 \over 3}\sqrt {{{20} \over 3}} ,{2 \over 3}$$ is

A
$${1 \over 3}$$
B
1
C
$${2 \over 5}$$
D
$$\sqrt {{2 \over 3}}$$
3
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
4
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.
WB JEE Subjects
Physics
Mechanics
Electricity
Optics
Modern Physics
Chemistry
Physical Chemistry
Inorganic Chemistry
Organic Chemistry
Mathematics
Algebra
Trigonometry
Coordinate Geometry
Calculus
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