Difference between revisions of "2020 AMC 12B Problems/Problem 2"
Advancedjus (talk | contribs) (Created page with "==Problem== What is the value of the following expression? <cmath>\frac{100^2-7^2}{70^2-11^2} \cdot \frac{(70-11)(70+11)}{(100-7)(100+7)}</cmath><math>\textbf{(A) } 1 \qquad...") |
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− | ==Problem== | + | == Problem == |
+ | What is the value of the following expression? | ||
+ | |||
+ | <cmath>\frac{100^2-7^2}{70^2-11^2} \cdot \frac{(70-11)(70+11)}{(100-7)(100+7)}</cmath> | ||
+ | |||
+ | <math>\textbf{(A) } 1 \qquad \textbf{(B) } \frac{9951}{9950} \qquad \textbf{(C) } \frac{4780}{4779} \qquad \textbf{(D) } \frac{108}{107} \qquad \textbf{(E) } \frac{81}{80} </math> | ||
− | + | == Solution == | |
− | <cmath>\frac{100^2-7^2}{70^2-11^2} \cdot \frac{(70-11)(70+11)}{(100-7)(100+7)}</cmath>< | + | Using difference of squares to factor the left term, we get |
+ | <cmath>\frac{100^2-7^2}{70^2-11^2} \cdot \frac{(70-11)(70+11)}{(100-7)(100+7)} = </cmath> | ||
+ | <cmath>\frac{(100-7)(100+7)}{(70-11)(70+11)} \cdot \frac{(70-11)(70+11)}{(100-7)(100+7)}</cmath> | ||
+ | Cancelling all the terms, we get <math>\boxed{\textbf{(A) 1}}</math> as the answer. | ||
− | ==Solution== | + | == Video Solution == |
+ | https://youtu.be/WfTty8Fe5Fo | ||
− | + | ~IceMatrix | |
− | {{AMC12 box|year=2020|ab=B|num-b=1|num-a= | + | == See Also == |
+ | {{AMC12 box|year=2020|ab=B|num-b=1|num-a=3}} | ||
{{MAA Notice}} | {{MAA Notice}} |
Revision as of 14:28, 19 January 2021
Contents
Problem
What is the value of the following expression?
Solution
Using difference of squares to factor the left term, we get Cancelling all the terms, we get as the answer.
Video Solution
~IceMatrix
See Also
2020 AMC 12B (Problems • Answer Key • Resources) | |
Preceded by Problem 1 |
Followed by Problem 3 |
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.