Question

medal! please help
Find the missing term of the geometric sequence. 45, ____, 1620.
A) 51
B) 6
C) 270
D) 9720

Answer 1

\(\frac{x}{45}=\frac{1620}{x}\)

Answer 2

Solve for x

Answer 3

45x²=1620

Answer 4

x^2=1620*45 @SolomonZelman

Answer 5

You will have 2 means.

Answer 6

You options are INCOMPLETE.

Answer 7

@SolomonZelman x^2=1620*45
not 45x^2=1620

Answer 8

the option is there...

Answer 9

Nope

Answer 10

Look closer, you go ` r² ` from 45 to get 1620

Answer 11

So the common ratio can be -6 or 6.

Answer 12

if a,b,c is geometric b/a = c/b
so x/45=1620/x
ie
x^2=1620*45

Answer 13

you don't multiply them, it makes no sense

45 × r = missing mean
45 × r × r = 1620

45 r² = 1620 And then divide both sides by 45.

Answer 14

do you agree that if we have geometric series a,b,c,d... then b/a=c/d=d/c?

Answer 15

if you agree with that then you must agree with x/45 = 1620/x
then you also must agree that x^2=45*1620
then you must agree that x = 270

Answer 16

b/a = d/c (not c/d)

Answer 17

im doing b/a = c/b
here b = x
a = 45 , c = 1620

Answer 18

mine should say
b/a=c/b=d/c?

Answer 19

x × 45 = 1620 ÷ x

Like this

Answer 20

ok man...

Answer 21

where each side of the equation is equivalent to the missing mean

Answer 22

Or am I wrong ?

Answer 23

again for geometric sequence a,b,c
we MUST have b/a=c/b
here we have 45,x,1620
so
x/45=1620/x

Answer 24

I think I have made it clear that I think your wrong:P

Answer 25

or give me your answer and ill show its wrong:P

Answer 26

the one that is not an option that is.

Answer 27

My solution comes up with option C

Answer 28

45x^2=1620
x^2=1620/45 gives x = 6 is what you said before

Answer 29

I might be not good at math, but this I know for sure,

\(\huge\color{blue}{ t_{n}\times r=\frac{t_{n+2}}{r} }\)

Answer 30

if you are getting x = 720 then you changed something

Answer 31

No, 36 is r²

Answer 32

and r=6

Answer 33

or -6

Answer 34

lol I solved for x, the missing thing.
you solved for r

Answer 35

then you will find r to get the missing thing

Answer 36

:)

Answer 37

well, we are both solving for the common ratio.

Answer 38

you get 6 from x^2=1620/45
I get 270 from x^2=1620*45

Answer 39

we both need to define our variables:)

Answer 40

I get x=6 from x²=1620 / 45

Answer 41

and what makes no sense about what get ?

Answer 42

All I am saying is that the common ratio is 6 or -6, and there are 2 geometric means -270 or 270. And the best choice is C, even though it is not complete, since it is missing another mean of -270.

Answer 43

yes, again you solved for the ratio, I solved for the missing term. They should have put a 4th term on there to show that it would either be positive or negative.