x + y +z = 40 x = 2y 75x + 120y + 150z = 4.020 *tolong dijawab ya pakai cara determinan makasih

jawab
75 x +120  y +150 z = 4.020
atau
25x + 40 y + 50 z = 1.340
x - 2y = 0
x + y + z = 40

X = DX/D = 1320/-40 = -33
y = DY/D = -660/-40 = 16,5
z = Dz/D = 420/-40 = -10,5 [tex]D \ = \left[\begin{array}{ccc}25&40&50\\1&-2&0\\1&1&1\end{array}\right]\, det D \,= 25(-2) -40(1) +50(1) \ = -40\\ X \ = \left[\begin{array}{ccc}1340&40&50\\0&-2&0\\40&1&1\end{array}\right]\, det X \,= 1340(-2) -40(0) +50(80) \ = 1.320 \\ Y \ = \left[\begin{array}{ccc}25&1340&50\\1&0&0\\1&40&1\end{array}\right]\, det Y \,= 25(0) - 1340 (1) + 50(40) = -660 \\ Z \ = \left[\begin{array}{ccc}25&40&1340\\1&-2&0\\1&1&40\end{array}\right]\, det Z \,= 25(-80) -40(40) + 1340(3) \ = 420\\ [/tex]