Algebra.Com's Answer #606525 by Alan3354(69443)![\"\"](\"/images/stars/stars-13.gif\")  
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a.
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document.write( "What is the maximum value of this expression?
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document.write( "Without calculus:
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document.write( "f(x) = -5x^2 + 12x
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document.write( "The max is the vertex at x = -b/2a = -12/-10 = 1.2
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document.write( "f(1.2) = 14.4 - 7.2
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document.write( "= 7.2
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document.write( "b.
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document.write( "For which values of y will x be positive?
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document.write( "Find where y = 0
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document.write( " | Solved by pluggable solver: SOLVE quadratic equation (work shown, graph etc) | \n" );
document.write( "Quadratic equation  (in our case  ) has the following solutons:
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document.write( " For these solutions to exist, the discriminant  should not be a negative number.
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document.write( " First, we need to compute the discriminant :  .
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document.write( " Discriminant d=33 is greater than zero. That means that there are two solutions:  .
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document.write( " Quadratic expression  can be factored:
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document.write( " Again, the answer is: 0.593070330817254, -0.843070330817254.\n" );
document.write( "Here's your graph:
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document.write( "x = 0 at those 2 points, x1 & x2
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document.write( "y is positive for x < x1 and x > x2
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