Question

solve each system of equations:
3) x+2y=0
4x-z= 4
5y+z=-1

Answer 1

do you want to do it by matrix?

Answer 2

no by substitution or elimination

Answer 3

ok well if we add the second two equations we get
4x+5y=3

so we also have x+2y=0 solve this one for x and get x=-2y
plugged this into the other equation and solve for y

Answer 4

4(-2y)+5y=3 <solve for y

Answer 5

after you get y
remember that x=-2y so finding x will be like eating cake

Answer 6

hopefully you get the same z for both of those bottom equations

Answer 7

x+2y=0
x=-2y


4x-z=4
4(-2y)-z=4
-8y-z=4
-8y-4=z


5y+z = -1
5y + (-8y-4) = -1
5y -8y-4 = -1
-3y-4=-1
-3y=3
y=-1

Answer 8

x+2y=0
x+2(-1) = 0
x-2 = 0
x=2

4x-z=4
4(2)-z=4
8-z=4
-z=-4
z=4

Answer 9

-3y=3 => y=-1
x=-2y=-2(-1)=2

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4(2)-z=4 => z=4

5(-1)+z=-1 => z=4
ok good
just checking

Answer 10

oh ok thanks! haha i always mess up on these :/