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# Solving Inequalities watch

1. Solve:
3(1-2x) - 5(3x+2) > 0

I can do everything apart from figure out which way the inequality sign should go (the answers say wou should get -21x>7 and then the final answer is x<-1/3 ).
Thanks very much
2. (Original post by daviem)
Solve:
3(1-2x) - 5(3x+2) > 0

I can do everything apart from figure out which way the inequality sign should go (the answers say wou should get -21x>7 and then the final answer is x<-1/3 ).
Thanks very much
If you are dividing by a negative number, the inequalities switch directions.
3. (Original post by lizard54142)
If you are dividing by a negative number, the inequalities switch directions.
That's what I thought but I did:

-7>21x
-7/21>x
-1/3>x

so got the final answer but not the mark in between
4. (Original post by daviem)
That's what I thought but I did:

-7>21x
-7/21>x
-1/3>x

so got the final answer but not the mark in between
Well it looks like you have rearranged it in a different way than the mark scheme. Perhaps post all your working, from the beginning?
5. (Original post by lizard54142)
Well it looks like you have rearranged it in a different way than the mark scheme. Perhaps post all your working, from the beginning?
Sure, I did:

3-6x-15x-10 > 0

3-10>6x+15x

-7>21x

-7/21>x

-1/3>x
6. (Original post by daviem)
Sure, I did:

3-6x-15x-10 > 0

3-10>6x+15x

-7>21x

-7/21>x

-1/3>x
Looks good to me! They probably kept the x's on the left and moved the (3-10) across to the right instead, in the mark scheme.
7. (Original post by lizard54142)
Looks good to me! They probably kept the x's on the left and moved the (3-10) across to the right instead, in the mark scheme.
Oh ok, Thanks for your help
8. (Original post by daviem)
Oh ok, Thanks for your help
No problem

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