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Algebra/Algebra question system (12.7-1)


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

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


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


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