in the expansion of (x+y)^15 a certain term contains x^10. What is the exponent of y in this term?
a.8
b.9
c.11
d.5

Question

in the expansion of (x+y)^15 a certain term contains x^10. What is the exponent of y in this term?
a.8
b.9
c.11
d.5

asnaseer · Answer

in the binomial expansion of:$$(x+y)^{15}$$you know the first term will be $x^{15}$ and the last term will be $y^{15}$. every term in between will be of the form:$$Cx^ay^b$$where C is some constant and a+b=15

asnaseer · Answer

can you work out the answer now?

anonymous · Answer

no

asnaseer · Answer

think about it and re-read what I have written.
remember you are told the term in question has $x^{10}$ in it. so using my notation you know that a=10 therefore:

a   + b = 15
10 + b = 15

therefore b=?

anonymous · Answer

5

asnaseer · Answer

correct!

anonymous · Answer

thank you :)

asnaseer · Answer

yw :)

anonymous · Answer

ok and i have one more question

asnaseer · Answer

just type each question in the list to the left