Question

In the expression (x+y)^8, if x=0.3 and y=0.7, what is the numerical value of the third term?
0.010,
0.020,
0.058,
0.060, or
0.068

Answer 1

@iGreen

Answer 2

@phi @TheSmartOne

Answer 3

@thomaster @confluxepic

Answer 4

I assume using the binomial expansion ?

Answer 5

@AravindG

Answer 6

use
\[\left(\begin{matrix}n \\ k\end{matrix}\right)a^{n-k} \ b^k\]
where n is 8, "a" is 0.3 and "b" is 0.7
to find k for the third term start counting from 0
0 1 2
so k=2 is the third term. fill in the formula

\[\left(\begin{matrix}8 \\ 2\end{matrix}\right)0.3^{8-2} \ 0.7^2 \\
28 \cdot 0.3^6 \cdot 0.7^2 \\
28 \cdot 0.000729 \cdot 0.49
\]