How do you solve the inequality #x^2+x20 >= 0# ?
The answer key says #5 <= x <= 4#
The answer key says
1 Answer
Sep 1, 2017
It seems the answer key was for
The given problem has solution:
#x <= 5# or#x >= 4#
Explanation:
Given:
#x^2+x20 >= 0#
This factors as:
#(x+5)(x4) >= 0#
This will hold if any of the following:

#(x+5 > 0" "# and#" "x4 > 0)" "<=>" "x > 4# 
#(x+5 < 0" "# and#" "x4 < 0)" "<=>" "x < 5# 
#x+5 = 0" "<=>" "x = 5# 
#x4 = 0" "<=>" "x = 4#
Hence we find the solution set is:
#x in (oo, 5] uu [4, oo)#
That is:
#x <= 5" "# or#" "x >= 4#
It seems that the answer key was for a different problem, namely:
#x^2+x20 <= 0#