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Show that a^4b+1 - a is divisible by 30

6 Answers

come on , give some information regarding what are `a` and `b`

sry bhaiyya but nothing more given

HINT:

a^4b+1 - a

=a^4b*a - a

=a(a^4b - 1)

Factors of 30=30*1, 2*15, 3*10, 6*5.

In order to be divisible by 30, either a or (a^4b-1) must be divisible by 30.

For b=1

=a(a⁴-1)

this can be possible when a=2

Then 2(2⁴-1)=30

u call this a solution arka?

No man ..... I call this a HINT.

341

Hari Shankar ·2010-07-08 00:02:22

A hint would be more like: you have to prove divisibility by 2,3, and 5. Use Fermat's Little Theorem.

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