Another simple Algebra problem

[coder1]

I'm trying to solve this one.

4-(2x+1)<7-x

I was originally getting 7/11, but I know that is wrong.

When you have a negative in front of the parenthesis how do you handle that?

Thanks for any help from some of you math geeks

 

[Heisenberg]

An inequality is just like an equal sign, except when you divide you have to reverse the inequality. The negative just means minus everything in the parentheses.

 

[Shooters]

Just distribute the negative across the parentheses

4-2x-1 < 7-x

 

[agnitrate]

I get x > -4

4 - (2x + 1) < 7 - x
3 - 2x < 7 - x
-4 < x
x > -4

There ya go

p.s. i prefer being called math-capable not geetk

-silver

 

[Haircut]

I'm assuming that this is

4 * -(2x+1) < 7-x

If so, you get

-8x - 4 < 7-x
-7x - 4 < 7
-7x < 11
x> -(11/7)

 

[coder1]

Man you guys are quick. Thanks for the help. I tried it again and right before the end I got -x<4 Do you just redistribute the negative to the four so it looks like x<-4?
Thanks again for your help.

 

[notfred]

Originally posted by: coder1
I'm trying to solve this one.

4-(2x+1)<7-x

I was originally getting 7/11, but I know that is wrong.

When you have a negative in front of the parenthesis how do you handle that?

Thanks for any help from some of you math geeks

4-2x-1 < 7-x
3-2x < 7-x
3 < 7 + x
-4 < x

x > -4

 

[notfred]

Originally posted by: coder1
Man you guys are quick. Thanks for the help. I tried it again and right before the end I got -x<4 Do you just redistribute the negative to the four so it looks like x<-4?
Thanks again for your help.

if you multiply by a negative number, you have to reverse the ineqality also

example:

5 < 10

multiply by (-1)

-5 > -10

See why it needs to be reversed?

Same goes for

-x<4

mult by -1

x>-4

 

[coder1]

Here's another question. When you have something like -x=-1 can it be rewritten as x=1 And is that doe by multiplying both sides by -1?


Thanks again.

 

[Haircut]

Originally posted by: coder1
Here's another question. When you have something like -x=-1 can it be rewritten as x=1 And is that doe by multiplying both sides by -1?


Thanks again.

yes

 

[agnitrate]

Originally posted by: coder1
Here's another question. When you have something like -x=-1 can it be rewritten as x=1 And is that doe by multiplying both sides by -1?


Thanks again.

Exactly.

-silver

 

[notfred]

Originally posted by: coder1
Here's another question. When you have something like -x=-1 can it be rewritten as x=1 And is that doe by multiplying both sides by -1?


Thanks again.

yep, just multiply both sides by -1.

 

[Dacalo]

Originally posted by: coder1
Here's another question. When you have something like -x=-1 can it be rewritten as x=1 And is that doe by multiplying both sides by -1?


Thanks again.

yes

 

[coder1]

Thanks guys for all your help. I havn't touched algebra in 10 years. Trying to teach myself again.

 

[TonyB]

what are you in elementary school? this is baby math

 

[coder1]

lol, I would probably suck even at elem algebra.

 

[notfred]

Originally posted by: coder1
lol, I would probably suck even at elem algebra.

No offense, but this is elementary algebra