For the inequality on wolfram-alpha, how do you get the algebraic the solution x < 4 ? I only get x > 23/5 when solving algebraically.
I believe you have two cases:
1)
2)
You've only worked out case 1.
For case 2, you end up with . This is a condition and is satisfied whenever .
Hence, in the case where , the inequality is satisfied by all such x. That's where the comes from.