MathDB

9

Part of 2022 AMC 10

Problems(2)

Painting a Rectangle

Source: 2022 AMC 10A #9 / 2022 AMC 12A #7

11/11/2022
A rectangle is partitioned into 5 regions as shown. Each region is to be painted a solid color - red, orange, yellow, blue, or green - so that regions that touch are painted different colors, and colors can be used more than once. How many different colorings are possible? [asy] size(5.5cm); draw((0,0)--(0,2)--(2,2)--(2,0)--cycle); draw((2,0)--(8,0)--(8,2)--(2,2)--cycle); draw((8,0)--(12,0)--(12,2)--(8,2)--cycle); draw((0,2)--(6,2)--(6,4)--(0,4)--cycle); draw((6,2)--(12,2)--(12,4)--(6,4)--cycle); [/asy]
<spanclass=latexbold>(A)</span>120<spanclass=latexbold>(B)</span>270<spanclass=latexbold>(C)</span>360<spanclass=latexbold>(D)</span>540<spanclass=latexbold>(E)</span>720<span class='latex-bold'>(A) </span>120\qquad<span class='latex-bold'>(B) </span>270\qquad<span class='latex-bold'>(C) </span>360\qquad<span class='latex-bold'>(D) </span>540\qquad<span class='latex-bold'>(E) </span>720
AMCAMC 10AMC 122022 AMC2022 AMC 10a2022 AMC 12Acounting
nice telescoping series

Source: 2022 AMC 10B #9

11/17/2022
The sum 12!+23!+34!++20212022!\frac{1}{2!}+\frac{2}{3!}+\frac{3}{4!}+\dots+\frac{2021}{2022!} can be expressed as a1b!a-\frac{1}{b!}, where aa and bb are positive integers. What is a+ba+b?
<spanclass=latexbold>(A)</span> 2020<spanclass=latexbold>(B)</span> 2021<spanclass=latexbold>(C)</span> 2022<spanclass=latexbold>(D)</span> 2023<spanclass=latexbold>(E)</span> 2024 <span class='latex-bold'>(A)</span>\ 2020 \qquad<span class='latex-bold'>(B)</span>\ 2021 \qquad<span class='latex-bold'>(C)</span>\ 2022 \qquad<span class='latex-bold'>(D)</span>\ 2023 \qquad<span class='latex-bold'>(E)</span>\ 2024
AMCAMC 102022 AMC2022 AMC 10B