What is the coefficient of x^8 y^2 in the expansion of (x + y)^10?

The coefficient of is .

Step-by-step explanation:

By the binomial theorem we have that

.

where is known has a binomial coefficient and it can be compute by . The symbol stands for the factorial of , that is to say,  

So if you have then we can replace on the expression of the binomial theorem to obtain

In order to obtain the coefficient of we find the term where , that is to say,

. We conclude that the coefficient we were looking for is .

the correct answer is 45x

9×5=45 then add the x

step-by-step explanation:

hans did not square the 40-unit side; he merely multiplied it by 2.   incorrect.