Question

brian’s work is shown. where did he make a mistake? choose the first incorrect step in brian’s work. brian’s work 3k - 6 = 15 step 1 - 6 - 6 step 2 3k = 9 step 3 (3k)/3 = 9/3 step 4 k = 3 step 1, because he should not have subtracted 6 to isolate 3k step 2, because 15 - 6 ≠ 9 step 3, because he should not have divided by 3 to isolate k step 4, because (3k)/3 ≠ k

Explanation:

Step1: Analyze Step 1

To solve \(3k - 6 = 15\), we should add 6 to both sides (addition property of equality) to isolate \(3k\). Brian subtracted 6, which is incorrect. Let's check the other steps for completeness, but the first mistake is Step 1.

Step2: Check Step 2 (if needed)

If we follow Brian's wrong Step 1 (\(3k - 6 - 6=15 - 6\)), then \(3k - 12 = 9\), not \(3k = 9\). But the key is the first incorrect step, which is Step 1.

Step3: Check Step 3 (if needed)

Dividing by 3 to isolate \(k\) is correct (division property of equality), so Step 3 is not the first mistake.

Step4: Check Step 4 (if needed)

\(\frac{3k}{3}=k\) is correct, so Step 4 is not the first mistake.

Answer:

Step 1, because he should not have subtracted 6 to isolate \(3k\)