Question

What is the third term in the binomial expansion (x – y5 )3?

~9x 2y2
~3xy10
~15xy10
~3x 2y5

Answer 1

the third term will be the one with a single factor of x - it will be a constant times x times some power of y. So how could we find that term?

Answer 2

The way to do that would be to find all the different combinations that would give us a single factor of x. That would be \[x*(-y^5)*(-y^5)+(-y^5)*x*(-y^5)+(-y^5)*(-y^5)*x\]

Answer 3

that is equal to \[xy^{10}+xy^{10}+xy^{10}\]

Answer 4

which is \[3xy^{10}\] or the second choice.

Answer 5

Thank you~