Htydjtk

In fact, I want to know how can I remove space in the second sum of the first expression and also to have a good equations design represented with only one number. Here is the code:

documentclass{article}

usepackage{mathtools}

begin{document}

begin{align}

U_{c}(1) &= sum_{n=1}^{4}( U_{e}(n)timessum_{k=n+10}^{14}U_{Delta e}(k)) ; U_{c}(2)&= sum_{n=1}^{4}U_{e}(n)times U_{Delta e}(n+9)\ U_{c}(3)&= sum_{n=1}^{6}U_{e}(n)times U_{Delta e}(n+8); U_{c}(4)&= sum_{n=1}^{7}U_{e}(n)times U_{Delta e}(n+7)\

U_{c}(5)&= sum_{n=2}^{8}U_{e}(n)times U_{Delta e}(n+5); U_{c}(6)&= sum_{n=3}^{7}U_{e}(n)times U_{Delta e}(n+5)\

U_{c}(7)&= sum_{n=8}^{11}( U_{e}(n)timessum_{k=n-4}^{7}U_{Delta e}(k))

end{align}

end{document}

To have like:

The space is caused by the sum's subscript. If you remove the subscript's width, you get tight spacing. Also you miss an additional & in places where you put a ;, to start a new column with the alignment at the =.

documentclass{article}

usepackage{mathtools}

begin{document}

begin{equation}

left[begin{aligned}

  U_{c}(1) &= sum_{n=1}^{4}( U_{e}(n)timessum_{mathclap{k=n+10}}^{14}U_{Delta e}(k)) ;& U_{c}(2)&= sum_{n=1}^{4}U_{e}(n)times U_{Delta e}(n+9)\

  U_{c}(3)&= sum_{n=1}^{6}U_{e}(n)times U_{Delta e}(n+8) ;& U_{c}(4)&= sum_{n=1}^{7}U_{e}(n)times U_{Delta e}(n+7)\

U_{c}(5)&= sum_{n=2}^{8}U_{e}(n)times U_{Delta e}(n+5) ;& U_{c}(6)&= sum_{n=3}^{7}U_{e}(n)times U_{Delta e}(n+5)\

U_{c}(7)&= sum_{n=8}^{11}( U_{e}(n)timessum_{k=n-4}^{7}U_{Delta e}(k))

end{aligned}right]

end{equation}

end{document}

Some suggestions:

• Use side-by-side minipage environments, for the groups of 4 and 3 equations, respectively




• Inside the minipage environments, use equation and split environments to achieve the required style of equation numbering




• Replace all times directives with thinspace




• Enlarge the "outer" parentheses in the first and last equations on the right-hand side




• Use mathclap to "snug up" the spacing around the sum symbols in two cases




• Optional: replace all instances of U_{Delta with U_{!Delta, to tighten up the spacing between U and the subscript-Delta symbol

Still another suggestion/observation, echoing the remark by @Skillmon: If the large curly braces are placed on the left, as indicated by the screenshot you posted, it's not going to be easy for your readers to notice the equation numbers on the right. Assuming you want to go with the proposed layout, it may be (a lot) better if the large curly braces are placed on the right, so that they direct the reader's eye to the associated equation number.

documentclass{article}

usepackage{mathtools} % for 'mathclap' macro

begin{document}



%% First solution: Curly braces placed on left-hand side

noindent

begin{minipage}[t]{0.5linewidth}

begin{equation}

left{begin{split}

U_{c}(1)&= sum_{n=1}^{4}Bigl( U_{e}(n)

           sum_{mathclap{k=n+10}}^{14}U_{!Delta e}(k) Bigr) \ 

U_{c}(3)&= sum_{n=1}^{6}U_{e}(n), U_{!Delta e}(n+8) \

U_{c}(5)&= sum_{n=2}^{8}U_{e}(n), U_{!Delta e}(n+5) \

U_{c}(7)&= sum_{n=8}^{11}Bigl( U_{e}(n)

           sum_{mathclap{k=n-4}}^{7}U_{!Delta e}(k) Bigr)

end{split}right.

end{equation}

end{minipage}%

hfill  % maximize horizontal distance between the minipage environments

begin{minipage}[t]{0.47linewidth}

begin{equation}

left{begin{split}

U_{c}(2)&= sum_{n=1}^{4}U_{e}(n), U_{!Delta e}(n+9)\

U_{c}(4)&= sum_{n=1}^{7}U_{e}(n), U_{!Delta e}(n+7)\

U_{c}(6)&= sum_{n=3}^{7}U_{e}(n), U_{!Delta e}(n+5)

end{split}right.

end{equation}

end{minipage}



%% Second solution: Curly braces placed on right-hand side

noindent

begin{minipage}{0.5linewidth}

begin{equation}

left.begin{split}

U_{c}(1)&= sum_{n=1}^{4}Bigl( U_{e}(n)

           sum_{mathclap{k=n+10}}^{14}U_{!Delta e}(k) Bigr) \ 

U_{c}(3)&= sum_{n=1}^{6}U_{e}(n), U_{!Delta e}(n+8) \

U_{c}(5)&= sum_{n=2}^{8}U_{e}(n), U_{!Delta e}(n+5) \

U_{c}(7)&= sum_{n=8}^{11}Bigl( U_{e}(n)

           sum_{mathclap{k=n-4}}^{7}U_{!Delta e}(k) Bigr)

end{split}right}

end{equation}

end{minipage}%

hfill  % maximize horizontal distance between the minipage environments

begin{minipage}{0.47linewidth}

begin{equation}

left.begin{split}

U_{c}(2)&= sum_{n=1}^{4}U_{e}(n), U_{!Delta e}(n+9)\

U_{c}(4)&= sum_{n=1}^{7}U_{e}(n), U_{!Delta e}(n+7)\

U_{c}(6)&= sum_{n=3}^{7}U_{e}(n), U_{!Delta e}(n+5)

end{split}right}

end{equation}

end{minipage}



end{document}