math
posted by anthony on .
i need help with these problems please
[62x]<4
which is the numeral set for [2x]<5
1.[x]4<x<1]
2.{x]x<4orx>1}
3.{x]1<x<4}
4.{x]x<1orx>4}

You can treat greater than and less than signs kind of like equals signs by you can multiply both sides by a number and not change the result or add the same thing to both sides and not change the result.
The only thing you have to be careful about is when you multiply by 1 as the direction of the > or < changes.
Now:
6  2x < 4
 2x < 4  6
 2x < 2
When I multiply both sides by 1 the less than becomes a greater than.
2x > 2
x > 1
If you want the reason why the direction changes reply back to this.
Ok, part 2:
2x < 5
therefore x < 5/2
x < 2.5
1: 4<x<1 This interval is on the above interval
2: x<4 or x>1 doesn't as x can't be larger than 2.5 so x>1 fails.
3: 1<x<4 doesn't work as 4 is > 2.5
so it fails
4: x<1 or x>4 doesn't work as x>4 fails as x cannot be greater than 2.5
Ok, hope that helps!