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solve the system of equations algebraically

y=x^2-2x-3
y=x+1

2007-08-25 05:39:05 · 4 answers · asked by Anonymous in Science & Mathematics Mathematics

4 answers

y=x^2-2x-3
y=x+1

x + 1 = x^2 - 2x - 3
0 = x^2 - 3x - 4
0 = (x+1)(x-4)
x = -1, 4

y = -1+1 = 0
y = 4+1 = 5

The intersections are (-1,0) and (4,5).

2007-08-25 05:43:49 · answer #1 · answered by Kemmy 6 · 0 0

If you have two equations and two unknowns, they you can solve for the unknowns provided the equations are related in some way. For example you just substitute x + 1 for the y in the first equation. You will get the following:

x+1 = x^2 - 2x - 3.

you now have a simple quadratic.

0 = x^2 - 3x - 4
(x+1)(x-4)

if you substitute -1 or 4 in for x on either equation you find that y can either = 0 or 5

2007-08-25 12:56:17 · answer #2 · answered by Xash 3 · 0 0

take the second equation and substatute it into the first like this:

x+1 = x^2 - 2x -3

Now combine terms after subtracting x+1 from both sides to get:

x^2 - 3x - 4 = 0

Factor
(x-4)(x+1)=0
so
x = 4 OR x = -1 AND
y = 5 OR y = 0

2007-08-25 12:48:05 · answer #3 · answered by 037 G 6 · 0 0

equate y from botm sides

x+1=x^2-2x-3

simplify it.

If you cant make factors then use quadratic roots formula to find x

once you get x , calculate y .

2007-08-25 12:44:47 · answer #4 · answered by calculus 1 · 0 0

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