SOLUTION: y = x2 - 5x - 4 y = -2x2 - 4x - 2 I have to solve these using substitution and it is due today. I don't understand these and if I don't get them then I don't graduate. :(

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Question 1031874: y = x2 - 5x - 4
y = -2x2 - 4x - 2
I have to solve these using substitution and it is due today. I don't understand these and if I don't get them then I don't graduate. :(
Found 2 solutions by ankor@dixie-net.com, stanbon:
Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website!
y = x^2 - 5x - 4
y = -2x^2 - 4x - 2
Substitute (x^2 - 5x - 4) for y in the 2nd equation
x^2 - 5x - 4 = -2x^2 - 4x - 2
Combine like terms on the left
x^2 + 2x^2 - 5x + 4x - 4 + 2 = 0
3x^2 - x - 2 = 0
you can use the quadratic formula but this will factor to
(3x + 2)(x - 1)
3x = -2
x = -2/3
and
x = 1

Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website!
y = x2 - 5x - 4
y = -2x2 - 4x - 2
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Substitute for "y" and solve for "x"::
x^2 - 5x - 4 = -2x^2 - 4x - 2
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3x^2 - x - 2 = 0
Factor::
(3x+2)(x-1) = 0
x = -2/3 or x = 1
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Cheers,
Stan H.
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