Alevel Math Question help needed...!!!

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How to solve this inequality question?
(3x+1)(x+1)>0

Truly its easy question but i am confused that if we take (3x+1)>0 and (x+1)>0 then it shows answer wrong.... why is this so??????? please help
 
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It is incorrect because the inequality is equals to more than zero. They only want the values of x that will give you a positive value in the equation. This can be illustrated by plotting the graph.

The answers are:
x<-1 and x>-1/3
 
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It is incorrect because the inequality is equals to more than zero. They only want the values of x that will give you a positive value in the equation. This can be illustrated by plotting the graph.

The answers are:
x<-1 and x>-1/3
your answer is correct but please explain how you have done this and tell me the concept behind it.
 
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your answer is correct but please explain how you have done this and tell me the concept behind it.
Screen Shot 2015-03-01 at 11.41.56 PM.png
If you take a look at the graph above, you might understand it a little better. Since they only want values which are >0, you need to select the points where the value of the graph is more than zero. This is illustrated above. If you retain the signs by using x>-1, then you will be saying that the range will include values below the x-axis(which is negative). The green region that I marked is what you want as your answer so you need to change the signs when you encounter questions like this.

I hope it makes sense now.
 
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View attachment 50853
If you take a look at the graph above, you might understand it a little better. Since they only want values which are >0, you need to select the points where the value of the graph is more than zero. This is illustrated above. If you retain the signs by using x>-1, then you will be saying that the range will include values below the x-axis(which is negative). The green region that I marked is what you want as your answer so you need to change the signs when you encounter questions like this.

I hope it makes sense now.
which software or website did you use for making this graph?
 
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View attachment 50853
If you take a look at the graph above, you might understand it a little better. Since they only want values which are >0, you need to select the points where the value of the graph is more than zero. This is illustrated above. If you retain the signs by using x>-1, then you will be saying that the range will include values below the x-axis(which is negative). The green region that I marked is what you want as your answer so you need to change the signs when you encounter questions like this.

I hope it makes sense now.
Thank you very very much.. no i have understood it :)
 
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