Question

Mitchell solved a quadratic equation. His work is shown below.

In which step did Mitchell make an error?
5(x−2)² +6=86

5(x−2)²=80 Step 1

(x−2)²=16 Step 2

x²-2²=16 Step 3

x²=20 Step 4

x=±√20 Step 5

Answer 1

5(x-2)²+6=86

5(x²+4)+6=86

5x²+20=86-6

5x²=80

x²=80÷5

x²=16

✓x²=✓16

x=4

Answer 2

Step 3

Explanation:

(a - b)² is not a² - b².

Should have done:

Square root both sides after step 2