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The complete solution of the inequality [tex]\frac{1}{3}\left(\frac{2}{5} x+1\right) \geq \frac{1}{5}(x+4)[/tex] is

Sagot :

To solve the inequality [tex]\(\frac{1}{3}\left(\frac{2}{5} x + 1\right) \geq \frac{1}{5}(x + 4)\)[/tex], we need to follow several steps to manipulate the expression into a more workable form and solve for [tex]\(x\)[/tex]. Here is the step-by-step process:

1. Distribute and Combine Like Terms:

First, we distribute the fractions within the parentheses.
[tex]\[ \frac{1}{3}\left(\frac{2}{5} x + 1\right) = \frac{1}{3} \cdot \frac{2}{5} x + \frac{1}{3} \cdot 1 = \frac{2}{15} x + \frac{1}{3} \][/tex]
Similarly, for the right side:
[tex]\[ \frac{1}{5}(x + 4) = \frac{1}{5} x + \frac{4}{5} \][/tex]

2. Set Up the Inequality:

Now the inequality becomes:
[tex]\[ \frac{2}{15} x + \frac{1}{3} \geq \frac{1}{5} x + \frac{4}{5} \][/tex]

3. Eliminate Fractions by Finding a Common Denominator:

To simplify calculations, eliminate the fractions by multiplying everything by a common denominator. In this case, the smallest common multiple of 15, 3, and 5 is 15.
[tex]\[ 15 \left(\frac{2}{15} x + \frac{1}{3}\right) \geq 15 \left(\frac{1}{5} x + \frac{4}{5}\right) \][/tex]
Distributing the 15:
[tex]\[ 15 \cdot \frac{2}{15} x + 15 \cdot \frac{1}{3} \geq 15 \cdot \frac{1}{5} x + 15 \cdot \frac{4}{5} \][/tex]
Simplifying further:
[tex]\[ 2x + 5 \geq 3x + 12 \][/tex]

4. Isolate [tex]\(x\)[/tex] on One Side:

To isolate [tex]\(x\)[/tex], subtract [tex]\(2x\)[/tex] from both sides:
[tex]\[ 5 \geq x + 12 \][/tex]
Then subtract 12 from both sides:
[tex]\[ 5 - 12 \geq x \][/tex]
Which simplifies to:
[tex]\[ -7 \geq x \][/tex]

5. Rewrite the Solution:

This inequality can be rewritten as:
[tex]\[ x \leq -7 \][/tex]
Thus, the solution to the inequality [tex]\(\frac{1}{3}\left(\frac{2}{5} x + 1\right) \geq \frac{1}{5}(x + 4)\)[/tex] is:
[tex]\[ x \leq -7 \][/tex]
In interval notation, this solution set is [tex]\((- \infty, -7]\)[/tex].

So the complete solution of the inequality is:
[tex]\[ x \leq -7 \][/tex]