Solve the inequality....and justify your answer

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  • Thread starter Raerin
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In summary: That's exactly right. The Rational Root Theorem helps you narrow down the possible rational roots to try. Once you find one that works, you can use synthetic division to find the other roots and solve the inequality. In summary, to solve the inequality 12x^3 + 8x^2 ≤ 3x + 2, you can use the Rational Root Theorem to narrow down the possible roots, then use synthetic division to find the other roots and solve the inequality. This method involves solving the equality, taking the derivative and finding its roots, and using a sign chart to read off the solution.
  • #1
Raerin
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Solve the inequality 12x^3 + 8x^2 ≤ 3x + 2 and justify your answer.

To justify the answer do you need to make a sin chart and graph it?
 
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  • #2
How do you solve third degree polynom? Do you know what rational root Theorem is?
 
  • #3
Raerin said:
Solve the inequality 12x^3 + 8x^2 ≤ 3x + 2 and justify your answer.

To justify the answer do you need to make a sin chart and graph it?

Hi Raerin! :)

The usual approach is to first solve the equality.
Then take the derivative and find its roots.
Then you can make a sign chart to read off the solution (did you mean a sign chart instead of a sin chart?)

The first step is already not so easy for this particular problem.
As Petrus suggested, the easiest way to find the roots is by using the Rational root theorem.
Do you know of it?
 
  • #4
I like Serena said:
Hi Raerin! :)

The usual approach is to first solve the equality.
Then take the derivative and find its roots.
Then you can make a sign chart to read off the solution (did you mean a sign chart instead of a sin chart?)

The first step is already not so easy for this particular problem.
As Petrus suggested, the easiest way to find the roots is by using the Rational root theorem.
Do you know of it?
Oops, I made a typo, so yes, I do mean sign chart.
You're supposed to bring everything to one side, right? Then you find the number that would make the polynomial = 0?
 
  • #5
Raerin said:
Oops, I made a typo, so yes, I do mean sign chart.
You're supposed to bring everything to one side, right? Then you find the number that would make the polynomial = 0?

Yep!
 

FAQ: Solve the inequality....and justify your answer

What is an inequality?

An inequality is a mathematical statement that compares two quantities, expressing that one quantity is greater than, less than, or not equal to the other.

How do you solve an inequality?

To solve an inequality, you must isolate the variable on one side of the inequality sign and perform the same operation on both sides of the inequality until the variable is alone.

What is the difference between solving an equation and solving an inequality?

The main difference between solving an equation and solving an inequality is that equations have an equal sign, while inequalities have a greater than, less than, or not equal to sign. Inequalities also have a range of possible solutions, while equations typically have only one solution.

Why is it important to justify the solution of an inequality?

Justifying the solution of an inequality is important because it ensures that the solution is accurate and valid. It also helps to explain the reasoning behind the solution and provides evidence to support the answer.

What are some common mistakes when solving inequalities?

Some common mistakes when solving inequalities include forgetting to reverse the inequality symbol when multiplying or dividing by a negative number, incorrectly distributing a negative sign, and forgetting to switch the direction of the inequality when dividing by a negative number.

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