Lisa solved 3x2 + 1 = 28 as shown:
3x2 + 1 = 28
3x2 = 27
x2 = 9
She concluded that the solutions are x = -9 or x = 9.
1. Using complete sentences, explain what mistake she made.
2. What are the correct solutions?
The mistake is that she forgot to take both square roots of 9 = 3 or -3