Question 1168683: Kerwins father is 4 years more than five times as old as him.the product og their ages in years is 204.how old is kerwin? Found 3 solutions by ikleyn, josgarithmetic, greenestamps:Answer by ikleyn(52776) (Show Source):
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Kerwin's father is 4 years more than five times as old as him*. The product of their ages in years is 204. How old is Kerwin?
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* ("him" who? I assume you meant, "Kerwin".)
k, Kerwin
f, his father
The substitution and algebra steps should bring to ;
Discriminant is ,.....
-------Kerwin's age now
From that, Father's age is .
Solve informally and quickly by looking at pairs of positive integers with a product of 204 and finding a pair that satisfies the other condition.
1*204
2*102
3*68
4*51
6*34
12*17
34 is 4 more then 5 times 6....
ANSWER: Kerwin is 6 (his father is 34)
Suppose a formal algebraic solution was required. Then
x = Kerwin's age
5x+4 = father's age
You could try to factor that; but for most students that would be difficult.
You could of course go straight to the quadratic formula to find the answer. The use of the formula is straightforward; but in this case the required calculations are not easy.
So at this point, I personally would go to the informal solution shown above to find the answer is x=6, and then I would continue with the formal algebraic solution.
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