Another ab=, a+b= problem

[Jt00]

If ab=5 and a+b=4, then a³+b³=?
So far I have:
(a+b)³=a³+3a²b+3ab²+b³=4³
a³+b³+3a²b+3ab²=64
a³+b³+3ab(a+b)=64
a³+b³+3(5)(4)=64
a³+b³=4

But the only way a+b and a³+b³ could be the same would be if a and b were 1, which would mean a+b=2.
So is my answer right?

 

[tkhunny]

1) Why do you care? That is totally not the problem statement.

2) Are you assuming that a and b are greater than zero? Real?

 

[srmichael]

Hello dear ,
It looks your question is from A brief introduction to Grade VII math Curriculum and it's related topics .Your question is solved above .It's best5 answer.So i don't think it needy to answer it now .

Huh? :roll:

 

[Mrspi]

Amit is a pest who is trying to solicit customers for some site that tutors math for pay. He really should be banned.

And since Amit seems to be under the impression that ONLY DENIS is bothered by his continual "advertising attempts," I'm here to say that I'M bothered by them too.

 

[Deleted member 4993]

I finally figured out the process to ban a user - and did it!!!!

 

[Deleted member 4993]

Are you ever a Mr Scrooge !!

To-day is day after - day after -day after - day after that special day Tim!!!!!