Fill in the missing coefficients of the terms in the expansion of (x + y) ^9

1, 9, 36, 84, 126, 126, 84, 36, 9, 1.

Step-by-step explanation:

Using the binomial theorem:

(x + y) ^9 = x^9 + 9C1 x^8 y + 9C2 x^7y^2 + 9C3x^6y^3 + 9C4x^5y^4 + 9C5x^4y^5 +

9C6x^3y^6 + 9C7x^2y^7 + 9C8xy^8 + y^9

The coefficients are

1, 9, 36, 84, 126, 126, 84, 36, 9, 1.