Find Least Value Inequality for $$-1<x<0$$

In summary: So in summary, when solving for the least value of a term in the given range of $$-1 < x < 0$$, the correct approach is to plug in values and compare the results. This method shows that the term $1/x^3$ (option $E$) has the least value compared to $1/x$ (option $B$).
  • #1
Amad27
412
1
Which of the following have the least value if

$$-1 < x < 0$$

$$(A) -x$$
$$(B) 1/x$$
$$(C) -1/x$$
$$(D) 1/x^2 $$
$$(E) 1/x^3$$

Mmmmmmmm...

I'm not sure what to do, but I'll definitely try. We can break it up into two inequalities.

$$ x > -1$$
$$0 > x$$

$$\implies -x < 1, 0 < -x$$
$$\implies -1 < 1/x, 0 < 1/x$$
$$\implies 1 > 1/x, 0 > -1/x$$
$$\implies 1/x^2 < 1$$
$$ \implies 1/x^3 < -1$$

So $(E)$ should be correct.

BottomLine: Is this the correct way to go about it?

Thanks!
 
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  • #2
Olok said:
Which of the following have the least value if

$$-1 < x < 0$$

$$(A) -x$$
$$(B) 1/x$$
$$(C) -1/x$$
$$(D) 1/x^2 $$
$$(E) 1/x^3$$

Mmmmmmmm...

I'm not sure what to do, but I'll definitely try. We can break it up into two inequalities.

$$ x > -1$$
$$0 > x$$

$$\implies -x < 1, 0 < -x$$
$$\implies -1 < 1/x, 0 < 1/x$$
$$\implies 1 > 1/x, 0 > -1/x$$
$$\implies 1/x^2 < 1$$
$$ \implies 1/x^3 < -1$$

So $(E)$ should be correct.

BottomLine: Is this the correct way to go about it?

Thanks!

Hej + good morning,

Is this the correct way to go about it?
as usual in math there isn't the one and only way to do a question: If you get the correct result your way is probably correct too.

Here is how I would have done this question:
Let \(\displaystyle k \in \mathbb{R}\ \wedge \ k > 1~\implies~x = -\frac1k\)

If you look for the least value of a term all terms which produce a positive result are not valid. So that leaves the B and E. Now replace x by \(\displaystyle -\frac1k\) and you'll see immediately that \(\displaystyle \underbrace{-k^3}_{\text{case E}} < \underbrace{-k}_{\text{case B}}\)
 

FAQ: Find Least Value Inequality for $$-1<x<0$$

What is an inequality?

An inequality is a mathematical statement that compares two quantities using inequality symbols such as <, >, ≤, or ≥. It states that one quantity is less than, greater than, less than or equal to, or greater than or equal to the other.

What does "least value" mean in an inequality?

In an inequality, the "least value" refers to the smallest value that satisfies the given conditions. In the case of the inequality -1

How do I find the least value in an inequality?

To find the least value in an inequality, you need to look at the given range of values and identify the smallest number that satisfies the given conditions. In the case of -1

What is the difference between an inequality and an equation?

An inequality compares two quantities and shows their relationship, whereas an equation states that the two quantities are equal. In other words, an inequality indicates a range of values, while an equation shows a specific value.

Why is it important to find the least value in an inequality?

Finding the least value in an inequality is important because it helps us identify the smallest possible value that satisfies the given conditions. It is useful in many real-world scenarios, such as finding the minimum amount of a product to order or determining the lowest possible temperature for a chemical reaction to occur.

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