Mathematics
Holstine462
24

Find an equation for the nth term of a geometric sequence where the second and fifth terms are -2 and 16, respectively.

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YolandeSehl667

hello :  the nth term of a geometric sequence is :  Un = Up ×r^(n-p)    .   r is the common ratio  for : p=5 and n= 2 U5 = U2 ×r^3 16 = -2 r^3 r^3 = -8 but : -8 = (-2)^3 so :  r = -2 Un = U2 × r^(n-2) Un = -2 ×(-2)^(n-2)= (-2)^(n-2+1) the nth term of a geometric sequenceis : Un = (-2)^(n-1)

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