I have common ratio of 1.5 and the first term is 12 Ill post working in a sec
Let the first term be 'a' and let the common ratio be 'd'
a + ad^2 = 39 Equation 1
ad^3 + ad^5 = 131.625 Equation 2
a(1+d^2)=39 Equation 1 (factorised)
ad^3(1+d^2)=131.625 Equation 2 (factorised)
Then to eliminate...