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Interpolating Polynomial (Posted on 2025-01-12) Difficulty: 3 of 5
Let f(x) be a monic 4th degree polynomial such that f(1) = 1, f(2) = 8, f(3) = 27, f(4) = 64. Find f(5).

No Solution Yet Submitted by Danish Ahmed Khan    
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Solution computer solution | Comment 1 of 3
f(x)=x^4 + ax^3 + bx^2 + cx +d

1 + a + b + c + d = 1
16+8a+4b+2c+d = 8
81+27a+9b+3c+d=27
256+64a+16b+4c+d=64

Solving via Wolfram Alpha:

a = -9 and b = 35 and c = -50 and d = 24

In Matlab:

>> a = -9 , b = 35 , c = -50 , d = 24
a =
    -9
b =
    35
c =
   -50
d =
    24
>> for x=sym(1):5 x^4+a*x^3+b*x^2+c*x+d
end
ans =
1
ans =
8
ans =
27
ans =
64
ans =
149

f(5) = 149

Edited on January 12, 2025, 8:52 am
  Posted by Charlie on 2025-01-12 08:51:11

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