Since n=5, take the 6th row of Pascal Triangle: (a+b)⁵:
(a+b)⁵ = a⁵+5a⁴b+10a³b²+10a²b³+5ab⁴+b⁵.
But a= 2x and b=y, plug in:
(2x)⁵ + 5(2x)⁴y + 10(2x)³y² + 10(2x)²y³ + 5(2x)y⁴ +y⁵
32x⁵ + 80x⁴y +80x³y² + 40x²y³ + 10xy⁴ + y⁵
The 3rd term has a:
coefficient = 80
power of x= 3
power of y =2
