Find the error in the calculations below, if there is one:

Line (1)
: -5_<2x+7<9

Line (2)
: -12_<2x<2

Line (3)
: -6_<x<1

Line (4)
:

An image shows a number line. There is a filled-in circle at negative 6 and an open circle at positive 1. The number line is shaded between negative 6 and 1.

1 answer

Let's analyze the inequalities step by step to find any possible errors.

Starting with Line (1): \[ -5 \leq 2x + 7 < 9 \]

We can break this compound inequality into two parts.

Part 1:

\[ -5 \leq 2x + 7 \] Subtract 7 from both sides: \[ -5 - 7 \leq 2x \Rightarrow -12 \leq 2x \] Dividing both sides by 2: \[ -6 \leq x \quad \text{(or rewritten as } x \geq -6) \]

Part 2:

\[ 2x + 7 < 9 \] Subtract 7 from both sides: \[ 2x < 9 - 7 \Rightarrow 2x < 2 \] Dividing both sides by 2: \[ x < 1 \]

Now we can combine the results from both parts.

From Part 1, we have: \[ -6 \leq x \quad \text{(or } x \geq -6) \] From Part 2, we have: \[ x < 1 \]

Putting both parts together, we get: \[ -6 \leq x < 1 \]

This matches Line (3): \[ -6 \leq x < 1 \]

There are no errors in the statements or the final result: The number line has a filled-in circle at \(-6\) (indicating it is included) and an open circle at \(1\) (indicating it is not included). The shading from \(-6\) to \(1\) is correct.

In conclusion, none of the lines contain errors and thus all calculations appear to be correct.