Question

A g.p has 6 terms. If the third and fourth term are 28 and_56 respectively find the first term, the sum of the g.p and the product of the tenths and 20 term

Answer 1

Just translate the English into Math.
"If the third and fourth term are 28 and_56 respectively "
ar^2 = 28
ar^3 = 56
divide the second equation by the first.
r = 56/28 = 2

from ar^2 = 28
a(4) = 28
a = 7

Sum(6) = a(r^6 - 1)/(r-1)
= 7(2^6 - 1)/1= 441


You said, the GP has 6 terms, why are are finding stuff about
term10 and term20??
anyway .....
term(10) = 7(2^9)
term(20) = 7(2^19)

product = 49(2^28) , write it in scientific notation or whatever way you want