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Show that the number 510-310 is divisible by 11

5 Answers

30
Ashish Kothari ·

no one?

1
gauraviscool ·

we can solve it this like this........

510 - 310
=(52)5 - (35)2
=(11*2 +3)5 - (11*22 + 1)2
=(11q + 35) - (11p +12)
=11q +11p +242
=11(q+p+22)

1
Che ·

well from eulers theorem since 5 and 11 r coprime so 5^{\varphi (11)}\equiv 1mod11
\varphi (11)=10
so 5^10≡1mod11
similarly 3 and 11 r coprime so 3^10=1mod11
so 5^10-3^10=(1-1)mod11≡0mod11

11
Shaswata Roy ·

53≡4(mod 11)
(53)3≡43(mod 11)
510≡43X5(mod 11)

43X5≡1(mod 11)

Therefore,510≡1(mod 11)

35≡1(mod 11)
(35)2≡12(mod 11)
310≡1(mod 11)

510-310≡1-1(mod 11)
510-310≡0(mod 11)

OR

Since

510≡1(mod 11)

Let 510 be 11 k+1

310≡1(mod 11)

Let 310 be 11 m+1

Therefore

510 - 310 =11k+1 -11m-1
=11(k+m)

Hence it is divisible by 11

11
Shaswata Roy ·

There was just a small error which I have corrected:

11k+1-11m-1
=11(k-m)

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