Integral multiplication and division, fast` (1)a²-3a+——=(a - ——)² (2) Known: a + B = 9, a & # 178; + B & # 178; = 21, find ab=—— (3) If (x-3) (x + 3) = x & # 178; + ax + B, then the power of B is a=—— (4) Using (a + b) (a-b) = A & # 178; - B & # 178;, find (x + 2y-1) (x-2y + 1), the variant is—— (5) Given m + n = 2, Mn = - 2, then the value of (1-m) (1-N) is——

Integral multiplication and division, fast` (1)a²-3a+——=(a - ——)² (2) Known: a + B = 9, a & # 178; + B & # 178; = 21, find ab=—— (3) If (x-3) (x + 3) = x & # 178; + ax + B, then the power of B is a=—— (4) Using (a + b) (a-b) = A & # 178; - B & # 178;, find (x + 2y-1) (x-2y + 1), the variant is—— (5) Given m + n = 2, Mn = - 2, then the value of (1-m) (1-N) is——

(1) 9/4 3/2
(2) 30
(3) 1
(4) x^2-(2y-1)^2
(5) -3