Lorena solved the equation 5k – 3(2k – ) – 9 = 0. Her steps are below.

5k – 6k + 2 – 9 = 0
–k – 7 = 0
–k = 7
k =
Analyze Lorena’s work to determine which statements are correct. Check all that apply.

In Step 1, she correctly distributed –3 to the parentheses.
In Step 2, she combined like terms 5k and 2k.
In Step 3, she applied the multiplication property of equality to isolate the variable term.
In Step 4, she should have multiplied both sides by
–1 to isolate the variable.
Lorena found the correct solution to the linear equation.

1 answer

Let’s analyze Lorena’s work step by step:

The original equation is:

\[ 5k - 3(2k - 2) - 9 = 0 \]

Step 1: Distributing -3

  • Lorena writes: \(5k - 6k + 2 - 9 = 0\)

The correct distribution of \(-3(2k - 2)\) is \(-6k + 6\), not \(-6k + 2\). This means that her distribution step is incorrect.

Step 2: Combining like terms

  • Lorena represents the equation as \(-k - 7 = 0\)

Since the previous step was incorrect, combining the terms is also incorrect. The correct combination of terms after proper distribution should result in a different equation.

Step 3: Isolating the variable term

  • In her work, she moves from \(-k - 7 = 0\) to \(-k = 7\).

Since her previous steps were wrong, this step is also incorrect because it follows from the incorrect working equation.

Step 4: Multiplying or isolating the variable

  • She states that she isolated k correctly, but since the previous equations were wrong, this statement does not hold.

Finally, since her isolating method and each step stemmed from a miscalculation in distributing and combining like terms, Lorena did not find the correct solution.

Based on these analyses, we can conclude:

  1. In Step 1, she correctly distributed –3 to the parentheses. - False
  2. In Step 2, she combined like terms 5k and 2k. - False (Even if we assume she combined correctly, the terms were already incorrect.)
  3. In Step 3, she applied the multiplication property of equality to isolate the variable term. - False
  4. In Step 4, she should have multiplied both sides by –1 to isolate the variable. - True (this is generally the approach, but since her earlier steps are incorrect, this statement in the context of her work cannot be confirmed.)
  5. Lorena found the correct solution to the linear equation. - False

Thus, none of the statements apply as correct from the options given.