Question

The fifth term of (a - 3b)5 is 405ab4 is this true or false ?

Answer 1

true..

Answer 2

The k+1 term of (a+b)^n is \[\left(\begin{matrix}n \\ k\end{matrix}\right)a^{n-k}b^k\]

Answer 3

So the fifth term of (a-3b)^5 is\[\left(\begin{matrix}5 \\4\end{matrix}\right)a^{5-4}(-3b)^4=405ab^4\]

Answer 4

Notice that the fifth term gets k value of four....

Answer 5

thanckyou guys :)

Answer 6

welcome