1.Jika (X1,Y1) merupakan himpunan penyelesaian dari sistem persamaan 2x+5y = 12 dan x+4y = 15, nilai dari 5X + 3Y adalah....
2x+5y = 12 |x1| 2x + 5y = 12
x + 4y = 15 |x2| 2x + 8y = 30
---------------- -
-3y = -18
y = -18/-3
y = 18/3
subtitusikan
2x+5y = 12
2x +5(18/3) = 12
2x + 90/3 = 12
2x = 12 - 90/3
2x = 12 - 30
2x = -18
x = -18/2
x = -9
5x + 3y = 5.-9+ 3.18/3
= -45+ 54/3
= -45 + 18
= - 27
jawabannnya D. -27
2x+5y = 12 |x1| 2x + 5y = 12
x + 4y = 15 |x2| 2x + 8y = 30
---------------- -
-3y = -18
y = -18/-3
y = 18/3
subtitusikan
2x+5y = 12
2x +5(18/3) = 12
2x + 90/3 = 12
2x = 12 - 90/3
2x = 12 - 30
2x = -18
x = -18/2
x = -9
5x + 3y = 5.-9+ 3.18/3
= -45+ 54/3
= -45 + 18
= - 27
jawabannnya D. -27
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