Question 824555: the age of a man is twice the square of his son. eight years hence,the age of the man will be 4 years more than three times the age of his son.find their present age
Answer by TimothyLamb(4379)   (Show Source):
You can put this solution on YOUR website! ---
x = man
y = son
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x = 2yy
x + 8 = 3(y + 8) + 4
x + 8 = 3y + 24 + 4
-x + 3y + 20 = 0
-2yy + 3y + 20 = 0
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the above quadratic equation is in standard form, with a=-2, b=3, and c=20
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to solve the quadratic equation, by using the quadratic formula, copy and paste this:
-2 3 20
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this quadratic has two real roots (the x-intercepts), which are:
y = -2.5
y = 4
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negative age doesn't make sense for this problem, so use the positive root
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answer:
y = son = 4
x = man = 32
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