In the binomial expansion of (a - b)n, n = 5, the sum of 5th and 6th terms is 0, then a / b equals
Manish , 11 Years ago
Grade 12
Analytical Geometry> In the binomial expansion of (a - b)n, n ...
4 Answers
bharat bajaj
t5+ t6= 0
nC4an - 4(- b)4+nC5an - 5(- b)5= 0
Solving above equation, we get a / b = (n - 4) / 5
Thanks
nC4an - 4(- b)4+nC5an - 5(- b)5= 0
Solving above equation, we get a / b = (n - 4) / 5
Thanks
Bharat Bajaj
askiitians faculty
Ujwal hirishi
by using easy method
tr+1/tr = n-r+1/r
=>n-5+1/5=n-4/5 for r =5
it is a easy method which can be used to solve any iit problem
Vaishali Senad
A/C to question ;
t5 + t6 = 0 ——— (1)
Since, t(r+1)= nCr. a^(n-r). b^r
Therefore, from (1) ;
nC4. a^(n-4). (-b)^4 + nC5. a^(n-5). (-b)^5=0
nC4. a^(n-4). b^4=
Vaishali Senad
Sorry for incomplete answer
nC4. a^(n-4). b^4= nC5. a^(n-5). b^5
[a^(n-4). b^4] / [a^(n-5). b^5]= nC5/nC4
a^(n-4-n+5). b^(4-5)= nC5/nC4
So, a/b= nC5/ nC4
a/b = n!/(n-5)!4! x (n-4)!4!/n!
Therefore, " a/b= (n-4)/5. "
LIVE ONLINE CLASSES
Prepraring for the competition made easy just by live online class.
Full Live Access
Study Material
Live Doubts Solving
Daily Class Assignments
Other Related Questions on analytical geometry
- The locus of the point represented by x= t^2 +t+1 and y=t^-t+1 is
- The locus of the point represented by x= t^2 +t+1 and y=t^-t+1 is
analytical geometry
1 Answer Available
Last Activity: 3 Years ago
show that the centroids of the triangles of which three perpendiculars lie along the lines y=m1x,y=m2x,y=m3x lie on y(3+m2m3+m3m2+m1m2)=x(m1+m2+m3+3m1m2m3)
show that the centroids of the triangles of which three perpendiculars lie along the lines y=m1x,y=m2x,y=m3x lie on y(3+m2m3+m3m2+m1m2)=x(m1+m2+m3+3m1m2m3)
analytical geometry
1 Answer Available
Last Activity: 3 Years ago
A circle has its center on straight line 5x-2y+1=0 and cuts the x axis at two points whose absciasse are -5,3 find equation of the circle and it's radius.
A circle has its center on straight line 5x-2y+1=0 and cuts the x axis at two points whose absciasse are -5,3 find equation of the circle and it's radius.
analytical geometry
1 Answer Available
Last Activity: 3 Years ago
Prove that ax^2+by^2+cz^2 +2ux+2vy+2wz+d=0 represent a cone if u^2/a+v^/b+w^2/c=d
Prove that ax^2+by^2+cz^2 +2ux+2vy+2wz+d=0 represent a cone if u^2/a+v^/b+w^2/c=d
analytical geometry
1 Answer Available
Last Activity: 3 Years ago