The solution of the inequality x+7x−5+3x+12≥0 is
[1,3]∪(5,∞)
(1,3)∪(5,∞)
(−∞,1)∪(5,∞)
none of these
We have x+7x−5+3x+12≥0
⇒ 2x+14+3x2−14x−52(x−5)≥0⇒ 3x2−12x+92(x−5)≥0⇒ (x−1)(x−3)(x−5)≥0
From the sign scheme, x∈[1,3]∪(5,∞)