systems of equations and inequalities

[carey]

!)x+2y+z=2
2) x + y - z = 6
3) 2x + y – z = 7

1) x + y + z = 2
2) 2y = z
3) x - 2y + 2z = 1

y = x2 – 4x + 7
y = x + 1

Please help me with these three problems,I would be most grateful !

Carey
Arizona

[Math Tutor]

The first system
|x+2y+z=2
|x + y - z = 6
|2x + y – z = 7

the third equation is x + (x + y - z) = 7
from the second equation we have x + y - z = 6
so
x + (x + y - z) = 7 is equivalent to x + 6 = 7 so x = 1

[Roland]

Such is called systems of Linear equations.
You solve by extracting one variable like x from the first equation and replace it's value in the second line to get a linear equation with one variable y that you can solve.

You may see a video solution of this type of problem by following the link below

http://www.satfreepractice.com/math-vid ... tions.html