Question 926545
x = alan age
y = mom age
z = dad age
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y = xx
z = y + 2
x + y + z = 80
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z = xx + 2
x + xx + z = 80
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x + xx + xx + 2 = 80
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2xx + x - 78 = 0
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the above quadratic equation is in standard form, with a=2, b=1 and c=-78
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to solve the quadratic equation, by using the quadratic formula, copy and paste this:
2 1 -78
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 = 6
x = -6.5
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the negative root doesn't fit the problem statement, so use the positive root:
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x = 6
y = 6*6
z = 6*6 + 2
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x = alan age = 6
y = mom age = 36
z = dad age = 38
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answer:
L = 18 inches 
w = 5 inches 
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