The error occurs in Step 3.
The correct factorization should be x(x - 6) + 2(x - 6) = 0, but Hyung-eun mistakenly wrote it as x(x - 6) + 2(x - 6) = 0.
The correct equation should be x(x - 6) + 2(x - 6) = 0.
Hyung-eun is solving the quadratic equation x^2 - 4x -12 = 0 by grouping. Her work is shown below. At whic step does Hyung-eun first make an error?
Step 1: x^2 + (-6x) + 2x - 12 = 0
Step 2: (x^2 + (-6x)) + (2x - 12) = 0
Step 3: x (x + (-6)) + 2(x - 6) = 0
x(x - 6 ) + 2(x - 6) = 0
Step 4: (x + 6) (x - 2) = 0
Step 5: x + 6 = 0 or x - 2 = 0
x = -6 or x = 2
A. Step 3
B. Step 1
C. Step 4
D. Step 2
1 answer