If the first term of a G.P. is 5 and the sum of first three terms is 35/4. What is the common ratio?
Answer: C
Given \(a=5\). Sum of first three terms is \(a+ar+ar^2 = 5(1+r+r^2) = 35/4\). \(1+r+r^2 = 7/4 \Rightarrow 4+4r+4r^2=7 \Rightarrow 4r^2+4r-3=0 \Rightarrow (2r+3)(2r-1)=0\). So \(r=1/2\) or \(r=-3/2\).