Can someone please explain how to derive these types of questions asking for the closed-form solution? Please break it down in detail and write how you can approach these types of questions in a general way, if possible

Solution:

Q24. Derive the closed-form/analytical expression for the following infinite sum i=1(1+r)iCi. Assume r>0. Q24. First, observe that i=1(1+r)iCi=rC+i=1(1+r)iC(i1)=rC+1+r1i=1(1+r)iCi This implies that AA=rC+1+rA,=r2C(1+r)