s2 = s1 * q
s4 = s1 * q ^ 3
8 = s1 * q
40 = s1 * q ^ 3
s1 * q ^ 3 = s1 * q * q ^ 2
40 = s1 * q ^ 3 = ( s1 * q ) * q ^ 2 = 8 * q ^ 2
40 = 8 * q ^ 2
40 / 8 = q ^ 2
5 = q ^ 2
q = ± sqrt ( 5 )
You can construct two g.p.
1.
8 = s1 * g
8 = s1 / sqrt ( 5 )
s1 = 8 / sqrt ( 5 )
2.
8 = s1 * g
8 = s1 / - sqrt ( 5 )
s1 = - 8 / sqrt ( 5 )
If for a g.p. S2=8 and s4=80,find its first term and the common ratio.
2 answers
Sir answer a=2,r=3,