Question

Calculati suma tuturor nr de forma xy stiind ca xy=4x+3y

Answer 1

xy=4x+3y
x=1,2
y=0,1,2,3

4x=4,8
3y=0,3,6,9

xy=10,13,16,19,20,23,26,29
10+13+16+19+20+23+26+29=156

Answer 2

xy = 4x + 3y
xy + 12 = 4x + 3y + 12
xy – 4x – 3y + 12 = 12
(x – 3)(y – 4) = 12
12 = 1 * 12 = 2 * 6 = 3 * 4 = 4 * 3 = 6 * 2 = 12 * 1

x – 3 = 1                                  x = 4
y – 4 = 12                                y = 16             xy = 64

x – 3 = 2                                  x = 5
y – 4 = 6                                  y = 10             xy = 50

x – 3 = 3                                  x = 6
y – 4 = 4                                  y = 8               xy = 48

x – 3 = 4                                  x = 7
y – 4 = 3                                  y = 7               xy = 49

x – 3 = 6                                  x = 9
y – 4 = 2                                  y = 6               xy = 54

x – 3 = 12                                x = 15
y – 4 = 1                                  y = 5               xy = 75

Answer: 64 + 50 + 48 + 49 + 54 + 75 = …