WB JEE 2008 | Sequence and Series Question 2 | Mathematics

WB JEE 2008

MCQ (Single Correct Answer)

-0.25

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

$${2^{n + 2}} - n - 4$$

$$2({2^n} - 1) - n$$

$${2^{n - 1}} - n$$

$${2^{n + 1}} - 1$$

WB JEE 2008

MCQ (Single Correct Answer)

-0.25

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

$${1 \over 3}$$

$${2 \over 5}$$

$$\sqrt {{2 \over 3}} $$

WB JEE 2008

MCQ (Single Correct Answer)

-0.25

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

16 abc

4 abc

8 abc

3 abc

WB JEE 2008

MCQ (Single Correct Answer)

-0.25

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

$${1 \over a},b,{1 \over c}$$ are in A.P.

$${1 \over {bc}},{1 \over {ca}},{1 \over {ab}}$$ are in H.P.

ab, bc, ca are in H.P.

$${a \over b},{b \over c},{c \over a}$$ are in H.P.

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