SOLUTION: I am having a tough time solving this problem, any help would be much appreciated. solve an inequality (x)/(x+20)>(2)/(x+8) A. (-∞,-10) (-10,-8) (4,∞) B. (-&#873

Algebra ->  Inequalities -> SOLUTION: I am having a tough time solving this problem, any help would be much appreciated. solve an inequality (x)/(x+20)>(2)/(x+8) A. (-∞,-10) (-10,-8) (4,∞) B. (-&#873      Log On


   



Question 300795: I am having a tough time solving this problem, any help would be much appreciated.
solve an inequality (x)/(x+20)>(2)/(x+8)
A. (-∞,-10) (-10,-8) (4,∞)
B. (-∞,-8) (4,∞)
C. (-10,-8)
D. (-20,-10) (-8,-4)
E. (-∞,-20) (-10,-8) (4,∞)
I came up with E but I'm not sure if the answer is correct.

Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
%28x%29%2F%28x%2B20%29%3E%282%29%2F%28x%2B8%29
Look at the inequality and determine when the left hand side equals the right hand side.
+%28x%29%2F%28x%2B20%29=%282%29%2F%28x%2B8%29
x%28x%2B8%29=2%28x%2B20%29
x%5E2%2B8x=2x%2B40
x%5E2%2B6x-40=0
You can factor this quadratic,
%28x%2B10%29%28x-4%29=0
Two solutions: x=-10 and x=4
In addition, because of the x terms in the denominator, add the additional points when the denominator goes to zero.
x=-20 and x=-8
Set up a number line and break it up using these two points.
Region 1: (-infinity,+-20)
Region 2: (-20,+-10)
Region 3: (-10,+-8)
Region 4: (-8,4)
Region 5: (4,+infinity)
Choose points in each region and check the inequality in that region to see if it's valid or not.
Region 1: Pick x=-30.
%28x%29%2F%28x%2B20%29%3E%282%29%2F%28x%2B8%29
%28-30%29%2F%28-30%2B20%29%3E%282%29%2F%28-30%2B8%29
-30%2F-10%3E2%2F-22
3%3E-1%2F11
True, Region 1 is a valid region.
.
.
Region 2: Pick x=-15.
%28-15%29%2F%28-15%2B20%29%3E%282%29%2F%28-15%2B8%29
%28-15%29%2F%285%29%3E%282%29%2F%28-7%29
-3%3E-%282%2F7%29
False, Region 2 is not a valid region.
.
.
Region 3: Pick x=-9.
%28x%29%2F%28x%2B20%29%3E%282%29%2F%28x%2B8%29
%28-9%29%2F%28-9%2B20%29%3E%282%29%2F%28-9%2B8%29
9%2F11%3E-2
True, Region 3 is a valid region.
.
.
Region 4: Pick x=0.
%28x%29%2F%28x%2B20%29%3E%282%29%2F%28x%2B8%29
0%3E%282%29%2F%280%2B8%29
0%3E1%2F4
False, Region 4 is not a valid region.
.
.
Region 5: Pick x=10.
%28x%29%2F%28x%2B20%29%3E%282%29%2F%28x%2B8%29
10%2F30%3E2%2F18
1%2F3%3E1%2F9
True, Region 5 is a valid region.
.
.
.
(-infinity,+-20)U(-10,+-8)U(4,+infinity)
E is the correct answer.