Question
Question: For all x Ī R, if mx<sup>2</sup> – 9mx + 5m + 1 \> 0, then m lies in the interval –...
For all x Ī R, if mx2 – 9mx + 5m + 1 > 0, then m lies in the interval –
A
(–4/61, 0)
B
[0, 4/61)
C
(4/61, 61/4)
D
(–61/4,0]
Answer
[0, 4/61)
Explanation
Solution
m > 0, D < 0
Ž 81m2 – 4m (5m + 1) < 0
Ž 61m2 – 4m < 0
Ž m (61 m – 4) < 0
Ž m Ī (0, 4/61)
