document.write( "Question 973496: an approximate model for the average temp. of a city is given by -3/2m^2+20m+17, where m is the month(january=1, february=2 and so on).
\n" ); document.write( "1. When is the temp the highest (a non integer result means the corresponding part of the month e.g 1.5 equivalent to jan. 15),and what is the maximum value.
\n" ); document.write( "2.In this model the average temp. will cross 80 twice(on the way up and on the way down) and will stay above between these two dates. What are those dates? \n" ); document.write( "

Algebra.Com's Answer #595669 by Boreal(15235) $\"\"$ $\"About$

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-3/2m^2+20m+17\r
\n" ); document.write( "\n" ); document.write( "The vertex m value (date) is at -b/2a. That is -20/-3 = +6.67 (June 20)
\n" ); document.write( "At that time the temperature maximum is -1.5(400/9)+1200/9 +17= (600/9)+17=83.33 degrees.\r
\n" ); document.write( "\n" ); document.write( "-1.5 m^2 + 20 m -63 =0, moving 80 to the left\r
\n" ); document.write( "\n" ); document.write( "1.5^m^2 - 20 m +63=0\r
\n" ); document.write( "\n" ); document.write( "(1/3) * [20 +/- sqrt (400-378)] = (1/3) [20 +/- sqrt 22] sqrt 22=4.69
\n" ); document.write( "(1/3) 24.69=8.23 August 7
\n" ); document.write( "(1/3) 15.31=5.10 May 3\r
\n" ); document.write( "\n" ); document.write( " $\"graph+%28300%2C300%2C-1%2C15%2C-5%2C95%2C%28-3%2F2%29x%5E2%2B20x%2B17%29\"$ \n" ); document.write( "

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