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Algebra/Algebra question system (12.7-1)

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Question
I am told to solve the following system:
y = 2x^2 + 5x + 9
y = -4x + 5
Thank you for your time!

Answer
The y = 2x^2 + 5x + 9 factors.
Since 2 is prime, try (2x+ )(x+ ).
Since the 9 is 3*3, try (2x+3)(x+3).
Sure enough, multiplying the right side on the equation y = (2x+3)(x+3)
gives y = 2x^2 + 5x + 9.

Assuming we are trying to get y = 0, we need to have either 2x+3 = 0 or x+3 = 0.
Subtracting 3 from both sides on both equations gives 2x = -3 and x = -3.

The 2nd equation is solved already, for it is just x=-3.

The 1st equation needs to be divided by 2 on both sides.
That gives x = -3/2.  This is the same as x = -1.

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Scott A Wilson

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Any algebraic question you've got. That includes question that are linear, quadratic, exponential, etc.

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I have solved story problems, linear equations, parabolic equations. I have also solved some 3rd order equations and equations with multiple variables.

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MS at math OSU in mathematics at OSU, 1986. BS at OSU in mathematical sciences (math, statistics, computer science), 1984.

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