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Home Q & A Board Science-Related Homework Help Mathematics
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rkc4yc rkc4yc
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11 years ago
Katie is considering using the quadratic formula, while Micah wants to use the factoring method to find exact solutions of 5x2 ? 8x = 7. Using complete sentences, explain who has chosen the better method and why.
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wrote...
#1
11 years ago
The quadratic formula is the better choice because the solutions are decimal numbers and cannot be found using the factoring method.  The factoring method only applies on exact solutions for integers but not decimals whereas the quadratic formula gives exact answers for integers and decimals.
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#2
11 years ago
5x^2 - 8x - 7 = 0

hmmm... that doesn't seem to factor very easily.

Using the quadratic seems faster and simpler.
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#3
11 years ago
The equation can be rewritten as 5x^2-8x-7=0.  The discriminant of the quadratic is b^2-4ac=64-4(5)(-7)=204, which is not a perfect square.  So Micah can try to factor the polynomial for hours and never stumble upon the correct factorization
5 (x-(8+sqrt(204))/10) (x-(8-sqrt(204))/10), which Katie can find quickly using the quadratic formula.
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