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Find the error in the calculations below:

Line (1): [tex]-3(2x + 5) \ \textless \ 21[/tex]
Line (2): [tex]-6x - 15 \ \textless \ 21[/tex]
Line (3): [tex]-6x \ \textless \ 36[/tex]
Line (4): [tex]x \ \textless \ -6[/tex]

The error occurred from:
A. Line (2) to Line (3).
B. Line (4) to Line (5).
C. Line (3) to Line (4).
D. Line (1) to Line (2).


Sagot :

Let's carefully review the steps to identify the mistake in the inequality solving process.

Given inequality:
[tex]\[ -3(2x + 5) < 21 \][/tex]

### Step-by-Step Solution:

Line (1) to Line (2):
Distribute the [tex]\(-3\)[/tex]:
[tex]\[ -3(2x) + (-3)(5) < 21 \][/tex]
This simplifies to:
[tex]\[ -6x - 15 < 21 \][/tex]
This transformation is correct.

Line (2) to Line (3):
Add 15 to both sides to isolate the term with [tex]\(x\)[/tex]:
[tex]\[ -6x - 15 + 15 < 21 + 15 \][/tex]
This simplifies to:
[tex]\[ -6x < 36 \][/tex]
This transformation is also correct.

Line (3) to Line (4):
Divide both sides by [tex]\(-6\)[/tex]. Note that dividing by a negative number reverses the inequality direction:
[tex]\[ \frac{-6x}{-6} > \frac{36}{-6} \][/tex]
This simplifies to:
[tex]\[ x > -6 \][/tex]
However, in the original line, it is stated as:
[tex]\[ x < -6 \][/tex]
which is incorrect since the inequality sign should flip when dividing by a negative number. This error occurs in this step.

So, the error is found in the step from Line (3) to Line (4).

Conclusion:
The error occurred from line (3) to line (4). The correct solution should have been:
[tex]\[ x > -6 \][/tex]

Therefore, the correct identification of the error is:
The error occurred from line (3) to line (4).