SOLUTION: I have to find x and y. X squared +2x-8 and y= 2x+1 This is from aug 2012 regents. I am practicing for my regents test. Thank you, K

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: I have to find x and y. X squared +2x-8 and y= 2x+1 This is from aug 2012 regents. I am practicing for my regents test. Thank you, K       Log On


   

Question 757121: I have to find x and y.
X squared +2x-8 and y= 2x+1
This is from aug 2012 regents. I am practicing for my regents test. Thank you, K
Found 2 solutions by MathLover1, stanbon:
Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!

y=x%5E2%2B2x-8.......1 and
y=+2x%2B1..........2
______________here you have system to solve.....subtract 2 from 1
y-y=x%5E2%2B2x-8-%282x%2B1%29
0=x%5E2%2B2x-8-2x-1
or
x%5E2%2Bcross%282x%29-8-cross%282x%29-1=0
x%5E2-9=0
x%5E2=9
x=sqrt%289%29
x=3 or x=-3
now find y
y=+2x%2B1..........2..plug in x=3
y=+2%2A3%2B1
y=+7
and x=-3
y=+2%28-3%29%2B1
y=+-6%2B1
y=-5
so, intersection points are: (3,7) and (-3,-5)
see it on a graph:

+graph%28+600%2C+600%2C+-10%2C10%2C+-10%2C+10%2C+2x%2B1%2C+x%5E2%2B2x-8%29+

Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
I have to find x and y.
X squared +2x-8 and y= 2x+1
-------
y = x^2 + 2x - 8
y = 2x+1
------
x^2 + 2x -8 = 2x + 1
------
x^2 - 9 = 0
(x-3)(x+3) = 0
x = 3 or x = -3
----
If x = 3, y = 2x+1 = 7
If x = -3, y = 2x+1 = -5
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Cheers,
Stan H.
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