Question

Find the 10th term of the geometric sequence 9,- 18, 36, ...

Answer 1

Answer:

90 i think

Explanation:

$a^{1}$ = 9

$a^{2}$ = 18

d = ?

$a^{10}$ = ?

$a^{2} =a, + (n-1) d$

$18 = 9 + (2-1) d \\d=18-9 \\d=9$

$a ^{10}= a^{1} + (n-1)d \\\\a ^{10}= 9 + (10-1) (9)\\a ^{10}= 9+ (9 x 9)\\a ^{10}=9+8^{1} \\a^{10} = 90$