a) ab + a + b = 48 b) 57-ab=a+b c) 63-(a+b)=ab
ab + a.1 + b = 48 57=a+b+ab 63=ab+a-b
a(b+1)+b+1=48+1 57=a+b.1+ab 63=ab+a.1-b
a(b+1)+(b+1).1=49 57=a+b(a+1) 63=a(b+1)-b
(a+1)(b+1)=49 57+1=a+1+b(a+1) 63-1=a(b+1)-(b+1).1
Ta có bảng : 58=(a+1).1+b(a+1) 62=(a-1)(b+1)
a+1 1 7 49 58=(a+1)(b+1) Ta có bảng :
b+1 49 7 1 Ta có bảng : a-1 1 3 7 9 21 63
a 0 6 48 a+1 1 2 29 58 b+1 63 21 9 7 3 1
b 48 6 0 b+1 58 29 2 1 a 2 4 8 10 22 64
a 0 1 28 57 b 62 20 8 6 2 0
b 57 28 1 0