PolynomiaL

Let P(x)= x6+ ax5+ bx4+ cx3+ dx2+ ex+ f be a polynomial such tht -

P(1)=1, P(2)=2, P(3)=3, P(4)=4, P(5)=5 & P(6)=6.
We need to find the value of P(7).

[A Hint wud do perhaps.] [22]

3 Answers

106
Asish Mahapatra ·

Let f(x) = P(x) - x

This polynomial has 6 roots 1,2,3,4,5,6

So f(x) =k* (x-1)(x-2)(x-3)(x-4)(x-5)(x-6)

= (x-1)(x-2)(x-3)(x-4)(x-5)(x-6) = P(x)-x

(k=1 comparing coeff of x^6)

now putting x=7

6! = p(7) - 7

=> P(7) = 6!+7 = 727

62
Lokesh Verma ·

this one has been solved sometime back..

f(x)=x

then f(x)-x has 6 roots...

hence f(x)-x = (x-1)(x-2)(x-3)(x-4)(x-5)(x-6)

now solve..

13
Avik ·

Thnx bhaiyaa n asish...[1] (Replies at the speed of Sound! [4])

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