Question

Consider an infinite G.P. with first term a and common ratio r. Its sum is 4 and the second term is 3/4, then

• A. a = $\frac { 7 } { 4 }$ , r = $\frac { 3 } { 7 }$
• B. a = $\frac { 3 } { 2 }$ , r = $\frac { 1 } { 2 }$
• C. a = 2, r = $\frac { 3 } { 8 }$
• D. a = 3, r = $\frac { 1 } { 4 }$

Answer 1

Answer: (D)

a = 3, r = $\frac { 1 } { 4 }$

Answer 2

$\frac { a } { 1 - r }$ = 4, ar = $\frac { 3 } { 4 }$

3 = 16r – 16 r²

r = $\frac { 1 } { 4 } , \frac { 3 } { 4 }$

If r = $\frac { 1 } { 4 }$ so, a = 3

If r = $\frac { 3 } { 4 }$ so, a = 1