
Reduce[{1/2 (x + y) a == 28, 1/2 (a + b) y == 35, 1/2 x b == 21, (x + y) (a + b) == 28 + 35 + 21 + 56, x > 0, y > 0, a > 0, b > 0}, {x, y, a, b}]
x>0∧x=y∧a=56x+y∧b=84x+y
Bazi cozumler:
FindInstance[{1/2 (x + y) a == 28, 1/2 (a + b) y == 35, 1/2 x b == 21, (x + y) (a + b) == 28 + 35 + 21 + 56, x > 0, y > 0, a > 0, b > 0}, {x, y, a, b}, 4]
{{x→14,y→14,a→2,b→3},{x→1,y→1,a→28,b→42}{x→89,y→89,a→2889,b→4289},{x→134,y→134,a→1467,b→2167},}