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If 17200 is divided by 18, the remainder is—
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- 17
- 16
- 1
- 2
Correct Option: C
(17)200 = (18 – 1)200
With the help of binomial theorem we solve this question ,
(x + a)n = xn + nxn–1.a + | xn − 2a2 | + | xn − 3a3 + .....+ an | ||
1 × 2 | 1 × 2 × 3 |
We see that all the terms on the R.H.S. except an has x as one of its factor and hence are divisible by x. So, (x + a)n is divisible by x or not will be decided by an.
Let x = 18, a = – 1 and n = 200
∴ (18 – 1)200 is divisible by 18 or not will depend on (–1)200 as all other terms in its expansion will be divisible by 18 because each of them will have 18 as one of their factors.
(–1)200 = 1 (∵ 200 is even)
1 is not divisible by 18 and is also less than 18.
∴ 1 is the remainder.