Question

PLEASE HURRY Find the sum of the first 10 terms in the series: -3, 9, -27, 81... a. -14763 c. 44286 b. 4920 d. 59049

Answer 1

Answer:

C.

Step-by-step explanation:

First find the pattern. The pattern is you multiply the number before by -3.

Just start with x as the first number.

x, -3x, 9x, -27x, 81x, -243x, 729x, -2187x, 6561x, -19683x

Add them all up: -14762

Now multiply by -3:

44286

Answer 2

Answer:

$\huge \boxed{\mathrm{\bold{C.} \ 44286}}$

Step-by-step explanation:

-3, 9, -27, 81...

The common ratio can be found by taking the quotient of a term in the sequence and the previous term.

$\displaystyle \frac{9}{-3} =-3$

The common ratio is -3.

A term in the sequence multiplies itself by -3 to get the next term.

The nth term for the sequence is : $a_n=(-3)^n$

The first 10 terms of the sequence are :

-3, 9, -27, 81, -243, 729, -2187, 6561, -19683, 59049

Adding these 10 terms :

-3 + 9 + -27 + 81 + -243 + 729 + -2187 + 6561 + -19683 + 59049

⇒ 44286