I don't get this question. (2 Viewers)

Dragonmaster262

Unorthodox top student
Joined
Jan 1, 2009
Messages
1,386
Location
Planet Earth
Gender
Male
HSC
2010
2 < l2x + 3l
2^2 < (2x + 3)^2
4 < 4x^2 + 12x + 9
0 < 4x^2 + 12x + 5
0 < (2x + 5)(2x + 1)
x < -5/2 and x > -1/2

l2x + 3l < 11
(2x + 3)^2 < 11^2
4x^2 + 12x + 9 < 121
4x^2 + 12x - 112 < 0
4 (x^2 + 3x - 24) < 0
4 (x + 5)(x - 3) < 0
-5 < x < 3

So when they intersect those are your solutions:
-5 < x < -5/2 AND -1/2 < x < 3 hope it helped : )
Yeah, I already knew that method and how to do that but I htought you were supposed to use some other method because it said solve simultaneously. I thought 'simultaneously' always involved elimination/substitution.
 

gurmies

Drover
Joined
Mar 20, 2008
Messages
1,209
Location
North Bondi
Gender
Male
HSC
2009
The solutions that have been provided ARE simultaneously solving. They are taking one case and combining with another case SIMULTANEOUSLY in order for both to be true for the original question...
 

Users Who Are Viewing This Thread (Users: 0, Guests: 2)

Top