Difference between revisions of "2025 AMC 12B Problems/Problem 1"

(Created page with "==Problem== What is the value of <math>\log_2({1+\sqrt{2}+\sqrt{3}})+\log_2({1+\sqrt{2}-\sqrt{3}})</math>? <math>\textbf{(A)}~1\qquad\textbf{(B)}~\frac{3}{2}\qquad\textbf{(C...")
 
(Solution)
Line 6: Line 6:
  
 
==Solution==
 
==Solution==
 +
 +
By log properties, we have <math>\log_2({1+\sqrt{2}+\sqrt{3}})+\log_2({1+\sqrt{2}-\sqrt{3}}) = \log_2({(1 + \sqrt{2})^{2} - 3})</math> because of difference of squares. Next, we need to simplify <math>\log_2({1 + 2\sqrt{2} + 2 - 3}) = \log_2{2^{\frac{3}{2}}} = \frac{3}{2}</math> hence <math>\frac{3}{2}</math> is the answer.
  
 
==See also==
 
==See also==
 
{{AMC12 box|year=2025|ab=B|before=First Problem|num-a=2}}
 
{{AMC12 box|year=2025|ab=B|before=First Problem|num-a=2}}
 
{{MAA Notice}}
 
{{MAA Notice}}

Revision as of 23:50, 28 July 2025

Problem

What is the value of $\log_2({1+\sqrt{2}+\sqrt{3}})+\log_2({1+\sqrt{2}-\sqrt{3}})$?

$\textbf{(A)}~1\qquad\textbf{(B)}~\frac{3}{2}\qquad\textbf{(C)}~2\qquad\textbf{(D)}~\frac{5}{2}\qquad\textbf{(E)}~3$

Solution

By log properties, we have $\log_2({1+\sqrt{2}+\sqrt{3}})+\log_2({1+\sqrt{2}-\sqrt{3}}) = \log_2({(1 + \sqrt{2})^{2} - 3})$ because of difference of squares. Next, we need to simplify $\log_2({1 + 2\sqrt{2} + 2 - 3}) = \log_2{2^{\frac{3}{2}}} = \frac{3}{2}$ hence $\frac{3}{2}$ is the answer.

See also

2025 AMC 12B (ProblemsAnswer KeyResources)
Preceded by
First Problem
Followed by
Problem 2
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

These problems are copyrighted © by the Mathematical Association of America, as part of the American Mathematics Competitions. AMC Logo.png