@Miracrown

Question

@Miracrown

vera_ewing · Answer

attachment

vera_ewing · Answer

@Miracrown It's D right? Can you check please?

miracrown · Answer

Nope unfortunately :(

vera_ewing · Answer

Oh then it has to be C right?

miracrown · Answer

To see this we first need to find what number each a_n value is multiplied times, to get the next one... Between the first two rows, what would we multiply 3 times to get -6 ?

vera_ewing · Answer

1 and -6?

♪chibiterasu · Answer

Only one term.

♪chibiterasu · Answer

Divide -6 and 3 and that is your common ratio.

♪chibiterasu · Answer

Which is going to be used in this sequence.

miracrown · Answer

$\color{blue}{\text{Originally Posted by}}$ @vera_ewing
Oh then it has to be C right?
$\color{blue}{\text{End of Quote}}$
Yes, its C. But you need to know why it is C, do you know?

vera_ewing · Answer

Thank you! And yes, I know why it's C, thanks to your explanation :)

♪chibiterasu · Answer

We have to remember the form of a geometric sequence.

$$a_n = a_1 \times r^{n-1}$$

♪chibiterasu · Answer

Where r is the ratio (-6/3 = >-2<) and a_1 is the first term (3).

miracrown · Answer

it's because each value of a_n in the chart gets multiplied times -2 to get the next a_n value
In other words, -2 is the "common ratio" between terms

Since our common ratio is -2 here, and the first term is 3, we can plug in a1 = 3 and r = -2 into this standard form ... That gives choice c