WB JEE 2018 | Sequence and Series Question 38 | Mathematics

WB JEE 2018

MCQ (Single Correct Answer)

-0.25

Given that n numbers of arithmetic means are inserted between two sets of numbers a, 2b and 2a, b where a, b $$ \in $$ R. Suppose further that the mth means between these sets of numbers are same, then the ratio a : b equals

n $$-$$ m + 1 : m

n $$-$$ m + 1 : n

n : n $$-$$ m + 1

m : n $$-$$ m + 1

WB JEE 2017

MCQ (Single Correct Answer)

-0.25

In a GP series consisting of positive terms, each term is equal to the sum of next two terms. Then, the common ratio of this GP series is

$${\sqrt 5 }$$

$${{\sqrt 5 - 1} \over 2}$$

$${{\sqrt 5 } \over 2}$$

$${{\sqrt 5 + 1} \over 2}$$

WB JEE 2016

MCQ (Single Correct Answer)

-0.25

If a, x are real numbers and | a | < 1, | x | < 1, then 1 + (1 + a) x + (1 + a + a²) x² + ..... $$\infty $$ is equal to

$${1 \over {(1 - a)(1 - ax)}}$$

$${1 \over {(1 - a)(1 - x)}}$$

$${1 \over {(1 - x)(1 - ax)}}$$

$${1 \over {(1 + ax)(1 - a)}}$$

WB JEE 2016

MCQ (Single Correct Answer)

-0.5

The sum of n terms of the following series $${1^3} + {3^3} + {5^3} + {7^3} + ...$$ is

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

$${n^3}(n - 1)$$

$${n^3} + 8n + 4$$

$$2{n^4} + 3{n^2}$$

WB JEE Subjects