Alg_Complete

# Plugging into the word equation gives 2007 paul

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Unformatted text preview: they are 300 miles apart. So, we have a right triangle here. That means that we can use the Pythagorean Theorem to say, ( 25t ) + ( 20 ( t - 2 ) ) 2 2 = ( 300 ) 2 This is a quadratic equation, but it is going to need some fairly heavy simplification before we can solve it so let’s do that. 625t 2 + ( 20t - 40 ) = 90000 2 625t 2 + 400t 2 - 1600t + 1600 = 90000 1025t 2 - 1600t - 88400 = 0 © 2007 Paul Dawkins 108 http://tutorial.math.lamar.edu/terms.aspx College Algebra Now, the coefficients here are quite large, but that is just something that will happen fairly often with these problems so don’t worry about that. Using the quadratic formula (and simplifying that answer) gives, 1600 ± 365000000 1600 ± 1000 365 32 ± 20 365 = = 2050 2050 41 t= Again, we have two solutions and we’re going to need to determine which one is the correct one, so let’s convert them to decimals. t= 32 + 20 365 = 10.09998 41 and t= 32 - 20 365 = -8.539011 41 As with the previous example the negative answer just doesn’t make any sense. So, it looks like the car A traveled for 10.09998...
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## This note was uploaded on 06/06/2012 for the course ICT 4 taught by Professor Mrvinh during the Spring '12 term at Hanoi University of Technology.

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