Which of the following represent the solution of the given inequality?
x2+2x+5≥0 ∀x∈R
Given: x2+2x+5≥0
⇒x2+1+2x+4≥0
Now use the identity: (a+b)2=a2+b2+2ab
⇒(x+1)2+4≥0
The LHS is always positive no matter what the value of x is. This is because the square of a number is always positive. And adding 4 to a positive number will also be positive. Hence {x:x∈R} is the solution set. So, the entire number line is the solution.