To the Editor:

In your Jan. 28 letters illustration of a harried teacher, it is easy to see why all the hands in the classroom are raised. The equation on the blackboard to the teacher's left is wrong!

Of course, we might assume that the teacher is trying to test the class's knowledge of the solution to a quadratic equation by erroneously placing the ''2a'' term under the square root symbol. But first-year algebra students know that ''2a'' divides all the terms on the righthand side and is not inside the square root. This is the correct equation:


Chester, N.J., Jan. 28, 2001