SOLUTION: Find all values of x for which the graph of f lies above the graph of g. (Enter your answer using interval notation.) f(x) = (1)/(x) g(x) = (1)/(x-7)

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Find all values of x for which the graph of f lies above the graph of g. (Enter your answer using interval notation.) f(x) = (1)/(x) g(x) = (1)/(x-7)       Log On


   



Question 1185633: Find all values of x for which the graph of f lies above the graph of g. (Enter your answer using interval notation.)
f(x) = (1)/(x) g(x) = (1)/(x-7)

Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


f%28x%29%3Eg%28x%29
f%28x%29-g%28x%29%3E0
1%2Fx-1%2F%28x-7%29%3E0

Add the two fractions with a common denominator

%28%28x-7%29-x%29%2F%28x%28x-7%29%29%3E0
%28-7%29%2F%28x%28x-7%29%29%3E0

The denominator, and therefore the whole expression, changes sign at x=0 and x=7.

(-infinity,0): both factors in the denominator are negative, so the denominator is positive, so the expression is negative. The inequality is not satisfied.

(0,7): one of the factors in the denominator is negative, so the denominator is negative, so the expression is positive. The inequality is satisfied.

(7, infinity): both factors in the denominator are positive, so the denominator is positive, so the expression is negative. The inequality is not satisfied.

ANSWER: The graph of f(x) (red) lies above the graph of g(x) (green) on the interval (0,7)

graph%28400%2C400%2C-10%2C10%2C-2%2C2%2C1%2Fx%2C1%2F%28x-7%29%29