Find and explain the error in the student’s work below.

Solve: 2m² - 7m - 30 = 0
2m² + 5m - 12m - 30 = 0
m(2m + 5) - 6(2m + 5) = 0
2m + 5)(m - 6) = 0
The student states that the answers are 2m + 5 and m - 6.

1 answer

The error in the student's work is that they incorrectly factored the expression 2m² - 7m - 30 as (2m + 5)(m - 6). The correct factorization is (2m - 15)(m + 2). Therefore, the correct solutions are m = 15/2 and m = -2, and not m = -5/2 and m = 6 as the student found.

Find and explain the error in the​ student’s work below.

The error in the student's work is that they incorrectly factored the expression 2m² - 7m - 30 as (2m + 5)(m - 6). The correct factorization is (2m - 15)(m + 2). Therefore, the correct solutions are m = 15/2 and m = -2, and not m = -5/2 and m = 6 as the student found.

Find and explain the error in the student’s work below.