Question

what is the coefficient of the fourth term in the expansion of (a-4b)^9? can you explain it too?

Answer 1

do you know pascal triangle?

Answer 2

yeah

Answer 3

ok, it takes time to get exponent of 9, but it works. or, do you want to get the way in discrete math use? much more faster. hehe

Answer 4

i did it up to 9 but it wasn't one of the answer choices

Answer 5

we have formula for this.

Answer 6

what's the formula?

Answer 7

ok, you mean pascal triangle?

Answer 8

i already tried pascal triangle but it didn't work. the fourth term in the triangle wasn't one of my answer choices

Answer 9

ok, show me your triangle.

Answer 10

I am sorry for making many question. I want to know which method you choose to do.

Answer 11

What have you gotten for a coefficient?

Answer 12

i got 84

Answer 13

The 4th term would have what powers on the variables?

Answer 14

and then,? your b is (-4b) not just b

Answer 15

84 a^6 + 4b^3

Answer 16

nope.

Answer 17

so the coefficient is -5376