First simplify, then evaluate: (a + 2) (A-2) + 2 (the square of a + 3), where a = 1 / 3. Given a = 2x + y, B = 2x-y, calculate the square of a-b

one
(a+2)(a-2)+2(a²+3)
=According to the formula: (a + b) (a-b) = A & # 178; - 4 + 2A & # 178; + 6;
=3a²+2
If a = 1 / 3, we can get:
(a+2)(a-2)+2(a²+3)
=3a²+2
=3×（1/9）+2
=7/3
two
A²-B²
=(A+B)(A-B)
=(2x+y+2x-y)(2x+y-2x+y)
=4x*2y
=8xy

First simplify, then evaluate: (a + 2) (A-2) + 2 (the square of a + 3), where a = 1 / 3. Given a = 2x + y, B = 2x-y, calculate the square of a-b

First simplify, then evaluate: (a + 2) (A-2) + 2 (the square of a + 3), where a = 1 / 3. Given a = 2x + y, B = 2x-y, calculate the square of a-b

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