Thread: Finding integer value of X

1. Finding integer value of X

For what integer value of X is 3x+5> 11 and x-3 <1?

2. Originally Posted by vaironxxrd
For what integer value of X is 3x+5> 11 and x-3 <1?
3x+5>11 holds for any x>2

x-3<1 holds for any x<4

CB

3. Originally Posted by CaptainBlack
3x+5>11 holds for any x>2

x-3<1 holds for any x<4

CB
So basically is just an Equation? Theres no different math behind it ... I thought there was a formula for that

4. Originally Posted by vaironxxrd
So basically is just an Equation? Theres no different math behind it ... I thought there was a formula for that
The information given just offered upper and lower bounds for x,
but you have to rewrite them.

$\displaystyle 3x+5>11\Rightarrow\ 3x+5>6+5\Rightarrow\ 3x>6\Rightarrow\ 3x>3(2)\Rightarrow\ x>2$

$\displaystyle x-3<1\Rightarrow\ x-3<4-3\Rightarrow\ x<4$

Then the allowable integer value(s) of x is much clearer.

5. Originally Posted by Archie Meade
The information given just offered upper and lower bounds for x,
but you have to rewrite them.

$\displaystyle 3x+5>11\Rightarrow\ 3x+5>6+5\Rightarrow\ 3x>6\Rightarrow\ 3x>3(2)\Rightarrow\ x>2$

$\displaystyle x-3<1\Rightarrow\ x-3<4-3\Rightarrow\ x<4$

Then the allowable integer value(s) of x is much clearer.
After you do 11-5 you get the 6 but i wonder why did you put 5 again... and 3(2) Where does that 2 come froM?

6. Originally Posted by vaironxxrd
After you do 11-5 you get the 6 but i wonder why did you put 5 again... and 3(2) Where does that 2 come froM?
It's just an alternative way.
Also, instead of dividing both sides by 3, I wrote 6=(3)2.

It's just an alternative way to see what 3x needs to be less than etc.

7. Originally Posted by Archie Meade
It's just an alternative way.