Question

solve the system by the method of substitution
-3x-3y+2z=-7
z=1
-2x-3y+z=-6
Options
A-(2,1,-1)
B-(2,-1,1)
C-(-2,1,1)
D-(2,1,1)
PLEASE SHOW WORK?????
PLEASE HELP ME????

Answer 1

Hint: replace z with 1 in the two given equations.

Answer 2

substitute z by 1 on equation 1 and equation 3.....then it will be simultaneous equatuon which is grade 10 staff

Answer 3

-3x-3y+2z=-7.....(i)
z=1......(ii)
-2x-3y+z=-6.....(iii)
substitute z=1 in equation (i) and (iii)
-3x-3y+2=-7.....(i')
-2x-3y+1=-6.....(iii')
they result to:
-3x-3y=-9.....(i')
-2x-3y=-7.....(iii')
from (i')
-3y= -9+3x
so substituting in (iii')
-2x-9+3x = -7
x =2
remember:
-3y= -9+3x
so
3y=9-3x
3y = 9-6
3y = 3
y=1
so solution:
(x,y,z)= (2,1,1), that's substitution, follow?