Two simple questions but wait (1 Viewer)

[FrankXie]

The questions are easy but wait do you really reckon you have solved them?

 

[glittergal96]

a. doesn't make sense because no real number a can satisfy those eqns, as log(5) > 3log(2) = log(8) => a < 1 => log(2) < 0, a contradiction.


b. 2p /(1+3p)=4/7 => p =2, but the series diverges if p=2 so there are no solutions.

 

[FrankXie]

nice. so my next question is

 

[glittergal96]

Just apply 2p/(1+3p) to the interval (-1,1). (well, excluding the domain hole obviously.)

You get something like (-inf,1/2) u (1,inf).

(On train without paper).

 

[dan964]

Using |r|<1
-1/3>p>1/3

which eventually gives
k<1/3 (where k is the limiting sum)

(I checked it with a graph)

It doesn't really converge when p = 1/3

 

[glittergal96]

What are you even trying to communicate here?

 

[FrankXie]

What are you even trying to communicate here?

lol to see whether students can see the errors in these questions, which are not made by me but I found from other resources like past papers or books

 

[glittergal96]

lol to see whether students can see the errors in these questions, which are not made by me but I found from other resources like past papers or books

Was referring to dans fragment of a sentence, your OP was good. .

 

[FrankXie]

Was referring to dans fragment of a sentence, your OP was good. .

lol anyway I don't think all students can detect the errors

 

[glittergal96]

lol anyway I don't think all students can detect the errors

Probably not, particularly the first one.