SOLUTION: The path of water from a hose on a fire tugboat can be approximated by the equation y = −0.0045x^2 + 1.25x + 5, where y is the height, in feet, of the water above the ocean w

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: The path of water from a hose on a fire tugboat can be approximated by the equation y = −0.0045x^2 + 1.25x + 5, where y is the height, in feet, of the water above the ocean w      Log On


   



Question 1182352: The path of water from a hose on a fire tugboat can be approximated by the equation
y = −0.0045x^2 + 1.25x + 5,
where y is the height, in feet, of the water above the ocean when the water is x feet from the tugboat. When the water from the hose is 7 feet above the ocean, at what distance from the tugboat is it? Round answer to nearest hundredth.

Answer by ikleyn(52778) About Me  (Show Source):
You can put this solution on YOUR website!
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The path of water from a hose on a fire tugboat can be approximated by the equation y = −0.0045x^2 + 1.25x + 5,
where y is the height, in feet, of the water above the ocean when the water is x feet from the tugboat.
When the water from the hose is 7 feet above the ocean, at what distance from the tugboat is it?
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Write equation as you read the problem


    −0.0045x^2 + 1.25x + 5 = 7. 


From the equation


    0.0045x^2 - 1.25x - 5  = -7,

    0.0045x^2 - 1.25x + 2 = 0.


Use the quadratic formula


    x%5B1%2C2%5D = %281.25+%2B-+sqrt%281.25%5E2+-+4%2A0.0045%2A2%29%29%2F%282%2A0.0045%29 = %281.25+%2B-+sqrt%281.5265%29%29%2F0.009 = %281.25+%2B-+1.236%29%2F0.009.


There are two roots


    x%5B1%5D = %281.25+-+1.236%29%2F0.009 = 1.61 ft     (in ascending branch).      ANSWER

and

    x%5B2%5D = %281.25+%2B+1.236%29%2F0.009 = 276.27 ft   (in desceding branch).     ANSWER

Solved.