Question

What is the value of Σ^3(4*(1/2)^I-1) I=1 ?

a.7/8
b.8
c.7/2
d.7

Answer 1

we are given

$\sum _{i=1}^3\:\left(4\left(\frac{1}{2}\right)^{i-1}\right)$

we can expand it

$\sum _{i=1}^3\:\left(4\left(\frac{1}{2}\right)^{i-1}\right)=4(\frac{1}{2} )^{1-1}+4(\frac{1}{2} )^{2-1}+4(\frac{1}{2} )^{3-1}$

now, we can combine it

and we get

$\sum _{i=1}^3\:\left(4\left(\frac{1}{2}\right)^{i-1}\right)=7$............Answer

Answer 2

The answer is D.7 i hopes this helped