Importance of Base 10

g ( x ) = ( 4 a 3 d ) x 5 + ( 4 b 3 e ) x 4 + ( 4 c 3 f ) x 3 + ( 4 d 3 a ) x 2 + ( 4 e 3 b ) x + 4 f 3 c \large{\begin{aligned} g(x) = &&(4a - 3d) x^5 + (4b - 3e) x^4 + (4c - 3f) x^3 \\ &+& (4d - 3a) x^2 + (4e - 3b) x + 4f - 3c \end{aligned}}

We define the function g ( x ) g(x) as above where a , b , c , d , e a,b,c,d,e and f f are single-digit natural numbers independent of x x . If g ( 10 ) = 0 g(10) = 0 , find the value of a + b + c + d + e + f a+b+c+d+e+f .


The answer is 27.

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1 solution

Rajen Kapur
Jul 10, 2015

Re-writing g(x) = 0, after transposing and putting x = 10, 4 ( a 1 0 5 + b 1 0 4 + c 1 0 3 + d 1 0 2 + e . 10 + f ) = 3 ( d 1 0 5 + e 1 0 4 + f 1 0 3 + a 1 0 2 + b . 10 + c ) 4(a 10^5 + b 10^4 + c 10^3 + d 10^2 + e .10 + f ) = 3( d 10^5 + e 10^4 + f 10^3 + a 10^2 + b . 10 + c) 4 a b c d e f = 3 d e f a b c \large{\rightarrow 4 \overline{abcdef} = 3 \overline{defabc}} 4000 a b c + 4 d e f = 3000 d e f + 3 a b c \rightarrow 4000 \overline{ abc} +4 \overline{ def} = 3000 \overline{ def} + 3 \overline{ abc} 3997 a b c = 2996 d e f \rightarrow 3997 \overline{ abc} = 2996\overline{ def} 571 a b c = 428 d e f . \rightarrow 571\overline{ abc} = 428 \overline{def.} It may be concluded from here that a b c = 428 \overline{abc} = 428 and d e f = 571. \overline{ def} = 571. Hence a + b + c + d + e + f = 27.

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