Difference between revisions of "2021 Fall AMC 12B Problems/Problem 7"
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− | By trying conditions in each choice, we find the correct answer is <math>\boxed{\textbf{(D) }x = z and y - 1 = x}</math>. | + | By trying conditions in each choice, we find the correct answer is <math>\boxed{\textbf{(D) }x = z \mbox{ and } y - 1 = x}</math>. |
~Steven Chen (www.professorchenedu.com) | ~Steven Chen (www.professorchenedu.com) |
Revision as of 21:27, 25 November 2021
- The following problem is from both the 2021 Fall AMC 10B #12 and 2021 Fall AMC 12B #7, so both problems redirect to this page.
Problem
Which of the following conditions is sufficient to guarantee that integers , , and satisfy the equation
and
and
and
and
Solution 1
Plugging in every choice, we see that choice works.
We have , so
Our answer is .
~kingofpineapplz
Solution 2 (Bash)
Just plug in all these options one by one, and one sees that all but fails to satisfy the equation.
For , substitute and :
Hence the answer is
~Wilhelm Z
Solution 3 (Strategy)
Looking at the answer choices and the question, the simplest ones to plug in would be equalities because it would make one term of the equation become zero. We see that answer choices A and D have the simplest equalities in them. However, A has an inequality too, so it would be simpler to plug in D which has another equality. We see that and means the equation becomes , which is always true, so the answer is
Solution 4
By trying conditions in each choice, we find the correct answer is .
~Steven Chen (www.professorchenedu.com)
2021 Fall AMC 12B (Problems • Answer Key • Resources) | |
Preceded by Problem 6 |
Followed by Problem 8 |
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 |
The problems on this page are copyrighted by the Mathematical Association of America's American Mathematics Competitions.