Recent content by quentinchin

you can solve it by using Newton-raphson method

Give you a hint...this is a geometric sequence where 3(-1)^n(0.5)^n = 3(-.5)^n

I know that my level just pre-U, but in my point of view about math is, it's doesn't matter how much knowledge or formula I know but what the most important thing is I must try to apply what I gained in surrounding of me. Just like mathematic induction I will also using it to solve other...

Maybe mathematic induction is the best way to prove this sort of question but if we too often using this kind of method, our mathematic level wouldn't go any further. I really do not know how to solve this question and I just get the answer from my friend after I asked this question. Is...

I really appreciate it, but do you guys overlook the question? The question is to <PROVE> that 3^(2n+1) + 2^(n+2) is divisible by 7 but not using induction method.

shame to tell that i still do not understand what is modular arithmetic and induction. Can give me an example?

hehe i found it but a bit complex. 3^(2n+1) + 2^(n+2) = 3(9^n) + 4(2^n) = 3(9^n) - 3(2^n) + 7(2^n) = 3(9-2)[9^(n-1) + 9^(n-2)*2 + ... + 9*2^(n-2) + 2^(n-1)] + 7(2^n) = 7[3(9^(n-1) + 9^(n-2)*2 + ... + 9*2^(n-2) + 2^(n-1) + 2^n] hence the equation 3^(2n+1) + 2^(n+2) is dividable by 7.

sorry? can you clarify (9^n mod 7) =(2^n mod 7) and finish it?

Can u prove it ?

hey guy help me to prove this question: 3^(2n+1) + 2^(n+2) is dividable by 7.