Question

Himpuna penyelesaian sistem persamaan :
x + y + z = 3
x - y + z = 1
2x + y - 3z = 10
adalah {(x,y,z)}. nilai dari 3x + 2y + 5z = ......

a. 6
b. 3
c. 2
d. -5
e. -8

Answer 1

X + y + z = 3
x - y + z = 1
---------------+
2x + 2z = 4

2x + y - 3z = 10
x - y + z = 1
-------------------+
3x - 2z = 11

2x + 2z = 4
3x - 2z = 11
----------------+
5x = 15
x = 3

2x + 2z = 4
6 + 2z = 4
2z = -2
z = -1

x-y+z=1
3-y-1=1
y = 1

3x + 2y + 5z = 9 + 2 - 5 = 6 (a)

Answer 2