aₙ=a₁*qⁿ⁻¹
a₁₂=a₁*q¹¹ a₁₂=a₇*q⁵
a₇=a₁*q⁶
75=a₁*q¹¹
40=a₁*q⁶
75=40*q⁵
[tex]q^5=\frac{75}{40}[/tex]
[tex]q=\frac{\sqrt[5]{60} }{2}[/tex] [tex]a_{1} =\frac{75}{(\frac{\sqrt[5]{60} }{2})^11 } =\frac{32*\sqrt[5]{60^4} }{45}[/tex]
aₙ=[tex]a_{n} =\frac{32*\sqrt[5]{60^4} }{45}*(\frac{\sqrt[5]{60} }{2} )^n^-^1[/tex]