[tex] \left[\begin{array}{ccc}x-y&4\\2&x+y\end{array}\right] [/tex] = [tex] \left[\begin{array}{ccc}2&4\\2&8\end{array}\right] [/tex] x²-y²=? [tex] \left[\be

(1) x - y = 2
x+ y = 8
x^2-y^2 = (x+y)(x-y)
= 8×2 = 16

(2) a + b = 2×2 = 4 [1]
x + y = 3×1 = 3 [2]
x - y = 4×6 = 24 [3]
a - b = 2×5 = 10 [4]
Eliminasi persamaan 1 dan 4
a+b=4
a-b =10
______+
2a = 14
a = 7
maka b = -3

Eliminasi Persamaan 2 dan 3
x+y=3
x-y=24
______+
2x=27
x = 27/2
maka
x+y = 3
27/2 + y = 3
27/2 + y = 6/2
y = (6-27)/2
y = -21/2

ax-by
7×27/2 - -3×-21/2
189/2 - 63/2
126/2
= 63

semoga membantu :)