Question 378767
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Hi,
For a Geometric Sequence with common ratio= r {{{a[n] = a[1]*r^(n-1)}}} Question States
{{{a[4] = a[1]*r^(4-1)=8}}}
{{{r^3 = 8/a[1]}}}
{{{a[10] = a[1]*r^(10-1)= a[1]*r^(9)=  512}}} 
{{{(a[1]/a[1]^3)*8^3= 512}}}
{{{ a[1]^2= 1 }}}
{{{a[1] = -1}}} as the and common ratio is given as negative {{{r^3 = 8}}} r= -2

CHECKING our answer by reviewing the first 10 terms of this sequence:
 -1, 2, -4, 8, -16, 32, -64, 128, -256, 512