Question

If the product of three terms in GP is 216 and their sum is 19.Find the GP.

Answer 1

\[a*ar*ar ^{2} = 216\]
\[a ^{3}r ^{3}\]
\[a ^{3}r ^{3}=6^{3}\]
ar=6

Am I right till here?

Answer 2

Yes, I think so.

Answer 3

so
6+6r+6r^2=19r?

Answer 4

idk after this..

Answer 5

a+ar+ar^2=19
6/r+6+36/r

Answer 6

Quadratic equation?

Answer 7

Is this eq. correct?
42+6r=19r

Answer 8

oops its not i guess :/

Answer 9

I have this
6(1+r+r^2)=19r

Answer 10

Wow... What's happening :|
Just start it again...

\[a \times ar \times ar^2 = 216\]\[(ar)^3 = 6^3\]\[ar= 6\]\[r=\frac{6}{a}\]

\[a + ar + ar^2= 19\]\[a + 6 + ar^2= 19\]\[a + ar^2= 13\]\[a + a(\frac{6}{a})^2= 13\]Got it so far?

Answer 11

Yes I did all this
Im stuck here :/
I have this 6(1+r+r^2)=19r

Answer 12

What I did is not the same as what you did. Please check it again. The reason I make r as the subject is because I don't have to change a in the equation.

Answer 13

yeah just realized!

Answer 14

Do you understand what I've done then??

Answer 15

wont we end up in cubes with this equation?
I got this too..

Answer 16

oh okay it gets eliminated

Answer 17

a^2-13a+36=0

Answer 18

Yup! a quadratic equation!

Answer 19

hey i got this before too :o but didn't get factors o.O

Answer 20

If I use the formula ill end up in decimal stuff..

Answer 21

okay got it thanks !

Answer 22

The answer should be beautiful!