Find the Roots (Zeros) f(x)=5x^6+x^2 log of x+x
Problem
Solution
Identify the domain of the function. Because the expression contains
ln(x) the variablex must be strictly greater than zero (x>0 .Set the function equal to zero to find the roots.
Factor out the common term
x from the expression.
Analyze the factors. Since
x>0 due to the natural log domain, the factorx can never be zero. Therefore, any root must satisfy the equation:
Evaluate the behavior of the remaining expression for
x>0 For allx≥1 the terms5*x5 x*ln(x) and1 are all positive, so the sum is strictly greater than zero.Check the interval
0<x<1 In this range,ln(x) is negative. However, asx approaches0 from the right,5*x5→0 x*ln(x)→0 and the constant term1 remains. Thus, the function approaches1 Determine if a sign change occurs. By calculating the derivative or testing values, it can be shown that
5*x5+x*ln(x)+1 remains positive for allx in the domain(0,∞) Conclude that there are no values of
x that satisfy the equation.
Final Answer
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