Difference between revisions of "2006 AMC 12A Problems/Problem 10"
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For how many real values of <math>x</math> is <math>\sqrt{120-\sqrt{x}}</math> an integer? | For how many real values of <math>x</math> is <math>\sqrt{120-\sqrt{x}}</math> an integer? | ||
− | <math> \mathrm{(A) \ } 3\qquad \mathrm{(B) \ } 6\qquad \mathrm{(C) \ } 9\qquad \mathrm{(D) \ } 10\qquad \mathrm{(E) \ } 11</math> | + | <math> \mathrm{(A) \ } 3\qquad \mathrm{(B) \ } 6\qquad \mathrm{(C) \ } 9\qquad \mathrm{(D) \ } 10\qquad \mathrm{(E) \ } 11</math>. |
== Solution == | == Solution == |
Revision as of 17:06, 24 September 2018
- The following problem is from both the 2006 AMC 12A #10 and 2006 AMC 10A #10, so both problems redirect to this page.
Problem
For how many real values of is
an integer?
.
Solution
For to be an integer,
must be a perfect square.
Since can't be negative,
.
The perfect squares that are less than or equal to are
, so there are
values for
.
Since every value of gives one and only one possible value for
, the number of values of
is
.
See also
2006 AMC 12A (Problems • Answer Key • Resources) | |
Preceded by Problem 9 |
Followed by Problem 11 |
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 | |
All AMC 12 Problems and Solutions |
2006 AMC 10A (Problems • Answer Key • Resources) | ||
Preceded by Problem 9 |
Followed by Problem 11 | |
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 | ||
All AMC 10 Problems and Solutions |
The problems on this page are copyrighted by the Mathematical Association of America's American Mathematics Competitions.