Sequences and Series Question (1 Viewer)

[qldbulls]

Sum of the first four terms of a geometric series is 468.
Sum of the next four terms (S8 - S4) is 292500 . Find first term and common ratio

Having trouble solving for r, thanks in advance

 

[kkk579]

 

[nsw..wollongong]

r u supposed to use the u rule for math adv?

 

[kkk579]

r u supposed to use the u rule for math adv?

r u talking abt it in regards to my solution? all i did was turn it into a quadratic im in y10 idk what’s the u rule lmao

 

[howcanibesmarter]

r u talking abt it in regards to my solution? all i did was turn it into a quadratic im in y10 idk what’s the u rule lmao

i think he means the substitution when u let r^4=u? Cus that was the only u in ur working but that isnt a rule

 

[kkk579]

i think he means the substitution when u let r^4=u? Cus that was the only u in ur working but that isnt a rule

Yeah that’s not a rule hence why i was confused when he said u rule lol

 

[nsw..wollongong]

dw i got it lmao, my class calls subbing by u the 'u rule'

 

[Average Boreduser]

r u supposed to use the u rule for math adv?

its an s&s question, exclusively an adv question

 

[nsw..wollongong]

my point was that only our ext class learned abt u subbing, the adv class doesn't use it.

 

[howcanibesmarter]

my point was that only our ext class learned abt u subbing, the adv class doesn't use it.

Isn't that for integration tho? The u-substituion. Advanced maths only uses reverse chain rule. As for factorising and solving quadratics, advanced students are expected to solve those types of questions (i.e. degree 4s like this case) since it's part of basic algebra

 

[nsw..wollongong]

no doubt that adv students should be able to solve basic algebra questions, I'm just speaking from personal exp that adv students opt for methods of solving these questions other than subbing for u (like it was done in the above question, 6 + r^4 = u). didn't think it was that big of a deal?

 

[Average Boreduser]

no doubt that adv students should be able to solve basic algebra questions, I'm just speaking from personal exp that adv students opt for methods of solving these questions other than subbing for u (like it was done in the above question, 6 + r^4 = u). didn't think it was that big of a deal?

so basically what ur saying is that you would've factorised that polynomial and solved from there? ( )

 

[nsw..wollongong]

so basically what ur saying is that you would've factorised that polynomial and solved from there? ( )

i haven't looked at the question in detail so idk? we weren't taught this method at all so I'm not sure whats ur point

 

[howcanibesmarter]

lol its all good calm down

 

[Average Boreduser]

lol its all good calm down

no. I want to win the fight.

 

[nsw..wollongong]

no. I want to win the fight.

what fight bruh
k u win

 

[Average Boreduser]

what fight bruh
k u win

thanks