I have a question of what i am doing wrong setting up the problems for Binomail expansion.
Example 1.
The Coefficient of x^7 in the expansion of (2x+3)^9
The way i attempted to solve this was 9C2 (2x)^7 (3)^2
i ended up with 648. The correct answer is 41,472
Example 2.
The third term ( i dont really understand the term buisness with pascals triangle) in the expansion of (x-3)^7
(x-3)^7 = 7C2 (x^5)(-3)^2
Can anyone help me through the explanation or process?
Example 1.
The Coefficient of x^7 in the expansion of (2x+3)^9
The way i attempted to solve this was 9C2 (2x)^7 (3)^2
i ended up with 648. The correct answer is 41,472
Example 2.
The third term ( i dont really understand the term buisness with pascals triangle) in the expansion of (x-3)^7
(x-3)^7 = 7C2 (x^5)(-3)^2
Can anyone help me through the explanation or process?
