SOLUTION: Twice a number is no less than 10 units from -1

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Question 1097235: Twice a number is no less than 10 units from -1
Found 3 solutions by math_helper, ikleyn, josgarithmetic:
Answer by math_helper(2461) About Me  (Show Source):
You can put this solution on YOUR website!

A number: x
Twice a number: 2x
No less than 10 units from -1: | 2x - (-1) | >= 10

| 2x + 1 | >= 10
Two cases to consider, the first is 2x + 1 <= -10
2x + 1 <= -10
2x <= -11
x <= -11/2

2nd case: 2x + 1 >= 10
2x + 1 >= 10
2x >= 9
x >= 9/2

The solution regions are +highlight%28x+%3C=+-11%2F2%29+ and +highlight%28x+%3E=+9%2F2%29+

Answer by ikleyn(52786) About Me  (Show Source):
You can put this solution on YOUR website!
.
Twice a number is no less than 10 units from -1
~~~~~~~~~~~~~~~~~~~~~~

For me, it is a MYSTERY what this post/this condition means . . .


And the best service from my side to the author of this post is to say that this formulation is mathematically incorrect . . .

In my view, not only it is mathematically incorrect formulation.
It is incorrect from the English grammar, word usage and the sentence construction point of view, too . . .


But if you change it in this way
    
    Twice a number is highlight%28located%29 no less than 10 units from -1


           or even better


    Twice a number is highlight%28located%29/highlight%28remoted%29 no closer than 10 units from -1

then everything will be in place . . .



Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
"a number", n
abs%282n-%28-1%29%29, difference between twice the number and negative 1.

abs%282n%2B1%29%3E=10, the description as an inequality.

2n%2B1%3E=10
2n%3E=9
n%3E=9%2F2
OR
2n%2B1%3C=-10
2n%3C=-11
n%3C=-11%2F2


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system%28EITHER%2Cn%3C=-11%2F2%2COR%2Cn%3E=9%2F2%29
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