Answer:
7
Step-by-step explanation:
Sigma notation means that you will add and continue adding using the function given. Furthermore, bottom number i = 1 is your starting point and the top number 3 is where you will stop the summation. So,
Let i = 1:
[tex]4(\frac{1}{2}^{1-1})=4(1)=4[/tex]
Let i = 2
[tex]4(\frac{1}{2}^{2-1})=4(\frac{1}{2})=\frac{4}{2}=2[/tex]
Let i = 3
[tex]4(\frac{1}{2}^{3-1})= 4((\frac{1}{2})^2 )=4\frac{1}{4}=\frac{4}{4}=1[/tex]
And so let's add up our results:
4+2+1=7
