Group the last three.
4a^2-(b^2+4c^2-4bc)
=4a^2-(b-2c)^2
=(2a+b-2c)(2a-b+2c)
b^2-a^2+2ac-c^2
=b^2-(a-c)^2
=(b+a-c)(b-a+c)
definition
Addition: the operation of combining two numbers into one number.
Subtraction: when two addends and one of them are known, the operation of finding the other addend.
Multiplication: the operation of finding the product of two numbers.
Division: the operation of finding another factor by knowing the product of two factors and one of them.