search
Log In
2 votes
274 views

how to solve such questions?

in Quantitative Aptitude
retagged by
274 views
0
is ans 15?
0
10 will be the answer when u r taking x^2 as common inside it will be 1+x^2+x^4+x^6.... now it simple GP question

using simple formula$\binom{N+r-1}{r}$*x^2r which is $\binom{5}{2}$
1

akshat sharma link for formula plZ

0
sorry bro for late reply
see this formula is commonly used in generating function topic and chocolate problem type question in combinotrics right now i dont have any link u can refer those topic (this is just inverse of (1-x)^n
0
here N=4,r=2
0
Pull out first x^2 ,so it becomes 1+x^2+.....

The outside x^2 becomes x^8 because of power 4,subtract this from x^12,...

So we need to find coefficient of x^4 here

Since this series is has even numbers ,it clearly says it has x of the form x^2r.  ,And we are finding x^4 and thus r=2

Here n= 4,r=2 hence ,(4+2-1,2)=10

1 Answer

1 vote

For those who have dikkat in generating function can see it here  (download image and and then change its position ) open it in paint for clear view


edited by
1

download it and zoom 

Related questions

1 vote
2 answers
1
343 views
Three identical inlet pipes were opened at 6:00 AM to fill up an empty container. At 8:30 AM, 2 identical pipes (having different rate from existing pipe's rate) are also opened. At 9:30 AM, it still required 1 more hour for all these pipes to fill up ... which were added at 8:30 AM can individually fill up the empty container in 40 hours, then the capacity of the container is ____________ m3.
asked Jan 18, 2019 in Quantitative Aptitude Shankar Kakde 343 views
0 votes
2 answers
2
369 views
A ball thrown upward satisfy the equation s=160 t - 20 t^2, where S is in m (meter) and t is in sec. what is the maximum height achieved by the ball ? (a) 80 (b) 160 (c) 240 (d) 320 According to me.. Here s=height reached by the ball. t=time taken by ... height the stone will have a velocity of zero (since it will stop at the highest point). So, v=0 than can anyone tell me where I am wrong ?
asked Jan 10, 2019 in Quantitative Aptitude Vikas123 369 views
0 votes
0 answers
3
222 views
Triangles ABC and CDE have a common vertex C with the side AB of triangle ABC being parallel to side DE of triangle CDE. If the length of side AB=4 cm and length of side DE=10 cm and perpendicular distance between sides AB and DE is 9.8 cm, then the sum of areas of ... CDE is ________ $cm^2$ . Now here I don't understand why they have taken BCD and ACE on the same line! Isn't this possible?
asked Jan 2, 2019 in Quantitative Aptitude MiNiPanda 222 views
...