Respuesta :
we are given
[tex] \sum _{i=1}^3\:\left(4\left(\frac{1}{2}\right)^{i-1}\right) [/tex]
we can expand it
[tex] \sum _{i=1}^3\:\left(4\left(\frac{1}{2}\right)^{i-1}\right)=4(\frac{1}{2} )^{1-1}+4(\frac{1}{2} )^{2-1}+4(\frac{1}{2} )^{3-1} [/tex]
now, we can combine it
and we get
[tex] \sum _{i=1}^3\:\left(4\left(\frac{1}{2}\right)^{i-1}\right)=7 [/tex]............Answer
