<PRE><B>Question 828684</B>
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s = d/t
t = d/s
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x = airplane speed
y = wind speed
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ta = 720/(x + y)
tb = 720/(x - y)
ta + tb = 10
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720/(x + y) + 720/(x - y) = 10
720(x - y)/(x + y)(x - y) + 720(x + y)/(x + y)(x - y) = 10
720(x - y) + 720(x + y) = 10(x + y)(x - y)
720x - 720y + 720x + 720y = 10(xx - xy + xy - yy)
1440x = 10(xx - yy)
10xx - 1440x - 10yy = 0
10xx - 1440x - 10*30*30 = 0
10xx - 1440x - 9000 = 0
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the above quadratic equation is in standard form, with a=10, b=-1440, and c=-9000
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to solve the quadratic equation, by using the quadratic formula, copy and paste this:
10 -1440 -9000
into this solver: https://sooeet.com/math/quadratic-equation-solver.php
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the quadratic has two real roots at:
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x = 150
x = -6
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the negative root doesn&#39;t fit the problem statement, so use the positive root:
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answer:
x = airplane speed = 150 mph
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Solve and graph linear equations:
https://sooeet.com/math/linear-equation-solver.php
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Solve quadratic equations, quadratic formula:
https://sooeet.com/math/quadratic-formula-solver.php
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Solve systems of linear equations up to 6-equations 6-variables:
https://sooeet.com/math/system-of-linear-equations-solver.php</PRE>