Given the system of equations:
(1) x−2y+4z=6
(2) 3x+y+5z=4
(3) 2x−y+3z=4
Add (2) and (3):
(3x+y+5z)+(2x−y+3z)=4+4
5x+8z=8 (Equation A)
Multiply (3) by 2: 4x−2y+6z=8 (Equation 3')
Subtract (1) from (3'):
(4x−2y+6z)−(x−2y+4z)=8−6
3x+2z=2 (Equation B)
From (B), 2z=2−3x. Substitute this into (A):
5x+4(2z)=8
5x+4(2−3x)=8
5x+8−12x=8
−7x=0⇒x=0
Substitute x=0 into (B): 3(0)+2z=2⇒2z=2⇒z=1.
Substitute x=0 and z=1 into (2):
3(0)+y+5(1)=4
y+5=4⇒y=−1.
Now, calculate 2x−3y+5z:
2(0)−3(−1)+5(1)=0+3+5=8.