Question

Tentukan nilai (xy)2 jika x dan y memenuhi sistem persamaan :
x(48-5y)=6y
x(4-y)= -3y
tolong dibantu kak (:

Answer 1

48 x - 5 xy = 6y...(1)
4x - xy = - 3y  ...(kalikan 5) --> 20x - 5xy = -15 y  ...(2) 
..
1 dan 2 eli,minasi
48 x - 5xy = 6y
20x - 5xy = -15y
---kurangkan---
28 x = 21 y
x : y = 21 : 28 = 3 ; 4
misal x = 3a dan y = 4a maka xy = 12 a²
sub ke 1 --> 48x - 5xy = 6y
48(3a) - 5(12a²) = 6(4a)
144 a - 60 a² = 24 a
60a²  = 144 a - 24 a
60 a² = 120 a
60 a = 120
a = 2
x = 3a= 6
y = 4a = 8
(xy)^2 = (6.8)^2 = 48^2 = 2.304