MTH 266 HW 2 Problem #1

Question

Is the following valid? Why or why not?

For square matrices A and B with Real entries: (A+B)² = A²+ AB+B²

Answer 1

Not valid

Try it with A = 2 by 2 identity matrix and B = 2 by 2 matrix with first row 1 2 and second row 3 4.