Posted by **Margie** on Thursday, November 2, 2006 at 7:03pm.

Use the Substitution method to solve the system of equations.

x + y = -4

x - y = 2

PLz HELP!!

I'M NOT BOB BUT I CAN HELP

ITS REALLY SIMPLE ALGEBRA

X + Y = -4......EQN 1

X - Y = 2.....EQN 2

From EQN 2, let

x = 2 + y

Substitute that into EQN 1

x - y = -4

(2+y) + y= -4

2 + 2y= -4

2y = -4-2

y = -6/2

y = -3

SUBST y= -3 in EQN 2

x -(-3) = 2

x + 3 = 2

x = 2-3

x= -1

Therefore

y = -3 and x = -1

x + y = -4

(2+y) + y= -4

2 + 2y= -4

2y = -4-2

y = -6/2

y = -3

Thanks,what abou this one?

Use the Substitution method to solve the system of equations.

x + y = 10

y = x + 8

Thanks,what abou this one?

Use the Substitution method to solve the system of equations.

x + y = 10

y = x + 8

just use the ones she helped you with before.

minus y on each side of one equation (IE x+y=10 is now x=10-y.

then fill in the 10-y for x in the second equation.

May be 2

help

x+y=10

y=x+8

I think it goes like this

x+x+8=10

2x+8=10

2x=10-8

2x=2 divide both sides by 2

x=1

1+y=10

y=10-1

y=9

x+y=10 replaced 1+9=10

y=x+8 replaced 9=1+8

was this a real problem to solve, or are you just testing me?

x+y=10

y=x+8

I think it goes like this

x+x+8=10

2x+8=10

2x=10-8

2x=2 divide both sides by 2

x=1

1+y=10

y=10-1

y=9

x+y=10 replaced 1+9=10

y=x+8 replaced 9=1+8

was this a real problem to solve, or are you just testing me?

x+y=10

y=x+8

I think it goes like this

x+x+8=10 (y is replaced by x+8)

2x+8=10 (add the x's to get 2x)

2x=10-8 (move 8 to the other side)

2x=2 divide both sides by 2

x=1

1+y=10

y=10-1

y=9

x+y=10 replaced 1+9=10

y=x+8 replaced 9=1+8

was this a real problem to solve, or are you just testing me?

x + 2 = -4 x - (-4) = 2

x + 2 - 2 = -4 - 2 x - (-4) + 4 = 2 + 4

x = 6 x = 6

checked: checked:

(-6) + 2 = -4 (6) - (-4) = 2

-4 = -4 2 = 2

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