Difference between revisions of "1982 AHSME Problems/Problem 20"

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Rearrange the equation to <math>y^2=x^3-x^2=x^2(x-1)</math>. This equation is satisfied whenever <math>x-1</math> is a perfect square. There are infinite possible values of <math>x</math>, and thus the answer is <math>\boxed{D: \text{Not Finite}}</math>
 
Rearrange the equation to <math>y^2=x^3-x^2=x^2(x-1)</math>. This equation is satisfied whenever <math>x-1</math> is a perfect square. There are infinite possible values of <math>x</math>, and thus the answer is <math>\boxed{D: \text{Not Finite}}</math>
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==See Also==
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{{AHSME box|year=1982|num-b=19|num-a=21}}
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{{MAA Notice}}

Latest revision as of 02:54, 30 June 2025

1982 AHSME Problems/Problem 20

Problem

The number of pairs of positive integers $(x,y)$ which satisfy the equation $x^2+y^2=x^3$ is

$\text {(A)} 0 \qquad  \text {(B)} 1 \qquad  \text {(C)} 2 \qquad  \text {(D)} \text{not finite} \qquad  \text {(E)} \text{none of these}$

Solution

Rearrange the equation to $y^2=x^3-x^2=x^2(x-1)$. This equation is satisfied whenever $x-1$ is a perfect square. There are infinite possible values of $x$, and thus the answer is $\boxed{D: \text{Not Finite}}$

See Also

1982 AHSME (ProblemsAnswer KeyResources)
Preceded by
Problem 19
Followed by
Problem 21
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
All AHSME Problems and Solutions

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