Square two of a + 2A (B + C) + (B + C) quadratic

Square two of a + 2A (B + C) + (B + C) quadratic

This is the inverse of (a + b) ² = A & #178; + 2Ab + B & #178
Consider B + C as a whole
Square two of a + 2A (B + C) + (B + C) quadratic
=(a+b+c)²