Infinite multiplication

[Loki123]

How do I calculate this?

 

[Loki123]

How do I calculate this? View attachment 32275

Is this correct

 

[R.M.]

Looks good to me. Another alternative: let the left hand side equal x, then cube both sides. This gives you 3x = x³. Solving that equation leads to your answer.

 

[blamocur]

Is this correct
View attachment 32276

 

[blamocur]

Looks good to me too, but in the line before the final result you seem to have a typo: [imath]\frac{a}{1-r}[/imath] ?

 

[Loki123]

Looks good to me too, but in the line before the final result you seem to have a typo: [imath]\frac{a}{1-r}[/imath] ?

That's the formula I found for infinite sum here:

 

[blamocur]

That's the formula I found for infinite sum here:

The video is unavailable, but I am guessing it would be [imath]\frac{r}{1-r}[/imath], i.e. [imath]r[/imath] instead of [imath]a[/imath] in the numerator.

 

[Loki123]

The video is unavailable, but I am guessing it would be [imath]\frac{r}{1-r}[/imath], i.e. [imath]r[/imath] instead of [imath]a[/imath] in the numerator.

a is supposed to be the first member of the sum
r is supposed to be what you multiply a with to get the second member

 

[blamocur]

a is supposed to be the first member of the sum
r is supposed to be what you multiply a with to get the second member

You are right, and I am wrong: forgot that they aren't always the same

 

[Steven G]

You are right, and I am wrong: forgot that they aren't always the same

Corner time! BTW, welcome to the forum.

 

[topsquark]

You are right, and I am wrong: forgot that they aren't always the same

You'll like the corner. I spend a lot of time there. I have a nice seat cushion and a microwave. Sometimes I bring my teddy bear.

-Dan

 

[Steven G]

You'll like the corner. I spend a lot of time there. I have a nice seat cushion and a microwave. Sometimes I bring my teddy bear.

-Dan

No, no, no! No microwave in the corner!

 

[topsquark]

No, no, no! No microwave in the corner!

Hey, it's not like it's plugged in. There's no electric back there.

-Dan

 

[BigBeachBanana]

Hey, it's not like it's plugged in. There's no electric back there.

-Dan

Indeed. It's not used to heat food, but rather to hold over your head while you're in the corner as a punishment.

 

[topsquark]

Indeed. It's not used to heat food, but rather to hold over your head while you're in the corner as a punishment.

I put my teddy bear in there so it has a place to sleep over those long weekends.

-Dan