Answers

2014-03-09T17:26:23+08:00
Using descarte's Rule of signs

7 is one of the zeros of f(x)

first get the numerical coeffiients of f(x) then divide it by 7

1       -16      86      -176        105      ...7...

______7____-63____161_____-105_________________
1        -9       23         -15           0

if the remeinder is 0 ...then 7 is a root of f(x)

..study more on descarte's Rule of signs... :D
hope it helps :D
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