# stuck on an inequality problem

• Sep 24th 2011, 01:16 PM
stuck on an inequality problem
I am able to solve regular inequalities but not this type

2x+1 < 5x-8
• Sep 24th 2011, 01:17 PM
Siron
Re: stuck on an inequality problem
What have you tried?
Put all the constant numbers to one side and also all the variables to one side. Can you do that?
• Sep 24th 2011, 01:20 PM
Re: stuck on an inequality problem
so 7x+7=0?

or

2x+1-5×-8=0

I tried both and still get stuck
• Sep 24th 2011, 01:26 PM
Plato
Re: stuck on an inequality problem
Quote:

I am able to solve regular inequalities but not this type

2x+1 < 5x-8

Step #1

\$\displaystyle 1<3x-8\$.

Carry on!
• Sep 24th 2011, 02:53 PM
freestar
Re: stuck on an inequality problem
Approach inequalities like a regular equation. The only thing you Must keep in mind is to flip the sign whenever you divide by a negative number.

Here's an example:

\$\displaystyle -1-5x < -3x + 7\$
\$\displaystyle -2x < 8\$
divide both sides by -2, therefore sign flips.
\$\displaystyle x > -4\$

Hope it helped.
• Sep 24th 2011, 04:43 PM
Re: stuck on an inequality problem
Quote:

so 7x+7=0?

or

2x+1-5×-8=0

I tried both and still get stuck

Because you have not taken the correct steps.

\$\displaystyle 2x+1<5x-8\$

Add 8 to both sides, the left is still less than the right
since 3<7, therefore 3+8<7+8 for example.

\$\displaystyle 2x+1+8<5x+8-8\$

\$\displaystyle 2x+9<5x\$

\$\displaystyle 5x>2x+9\$

Now subtract 2x from both sides.
This gets you to what is probably quite familiar to you.