Source
%@Dif:2
%\SpecialCoor
\par\vspace{1.5cm}
\psovalbox{\rnode{A}{3}}\rnode{B}{\underline{$a$}}\psovalbox{+\rnode{C}{2}}\rnode{D}{\underline{$a$}}$=(3+2)\times a=$\rnode{E}{5}\rnode{F}{$a$}
\hfill
$x+3x=$\psovalbox{\rnode{A1}{1}}\rnode{B1}{\underline{$x$}}\psovalbox{+\rnode{C1}{3}}\rnode{D1}{\underline{$x$}}$=(1+3)\times x=$\rnode{E1}{4}\rnode{F1}{$x$}
\hfill
\psovalbox{\rnode{A2}{$-3$}}\rnode{B2}{\underline{$b$}}\psovalbox{$-$\rnode{C2}{5}}\rnode{D2}{\underline{$b$}}$=(-3-5)\times b=$\rnode{E2}{$-8$}\rnode{F2}{$b$}
\ncarc[arcangle=60,offset=2mm]{<->}{A}{C}
\naput{\rnode{G}{\footnotesize$3+2$}}
\ncbar[nodesep=1mm,angle=90]{->}{G}{E}
\ncarc[arcangle=-60,offset=-1mm]{<->}{B}{D}
\nbput{\rnode{H}{}}
\ncbar[angle=-90]{->}{H}{F}
\ncarc[arcangle=60,offset=2mm]{<->}{A1}{C1}
\naput{\rnode{G1}{\footnotesize$1+3$}}
\ncbar[nodesep=1mm,angle=90]{->}{G1}{E1}
\ncarc[arcangle=-60,offset=-1mm]{<->}{B1}{D1}
\nbput{\rnode{H1}{}}
\ncbar[angle=-90]{->}{H1}{F1}
\ncarc[arcangle=60,offset=2mm]{<->}{A2}{C2}
\naput{\rnode{G2}{\footnotesize$-3-5$}}
\ncbar[nodesep=1mm,angle=90]{->}{G2}{E2}
\ncarc[arcangle=-60,offset=-1mm]{<->}{B2}{D2}
\nbput{\rnode{H2}{}}
\ncbar[angle=-90]{->}{H2}{F2}
\par\vspace{1cm}\par

{\bf Attention, les expressions suivantes ne peuvent pas être réduites.}
$3\underline{a}+2\underline{b}\kern2cm 2\underline{a}+3\underline{\phantom{1}}\kern2cm2\underline{a^2}+5\underline{a}$

Recopie et complète les expressions suivantes :
\Eqalign{ 3a+2a&=\hbox to 2.5cm{\dotfill}\kern1cm&x+5x&=\hbox to 2.5cm{\dotfill}\kern1cm&4a+2b&=\hbox to 2.5cm{\dotfill}\cr 5a+2&=\hbox to 2.5cm{\dotfill}&3b+7b&=\hbox to 2.5cm{\dotfill}&2a^2+3a^2&=\hbox to 2.5cm{\dotfill}\cr x^2+2x^2&=\hbox to 2.5cm{\dotfill}&4a^2+2a&=\hbox to 2.5cm{\dotfill}&4x-2x&=\hbox to 2.5cm{\dotfill}\cr -3x+5x&=\hbox to 2.5cm{\dotfill}&-2x-3x&=\hbox to 2.5cm{\dotfill}&-3x+2y&=\hbox to 2.5cm{\dotfill}\cr x-3x&=\hbox to 2.5cm{\dotfill}&2a-3a&=\hbox to 2.5cm{\dotfill}&-3a^2+5a^2&=\hbox to 2.5cm{\dotfill}\cr 4x-3x^2&=\hbox to 2.5cm{\dotfill}&-5x^2+2x^2&=\hbox to 2.5cm{\dotfill}&-c-c&=\hbox to 2.5cm{\dotfill}\cr -2c-c&=\hbox to 2.5cm{\dotfill}&-c-2&=\hbox to 2.5cm{\dotfill}&-2c-2c&=\hbox to 2.5cm{\dotfill}\cr 2x+2c&=\hbox to 2.5cm{\dotfill}&-x^2-4x^2&=\hbox to 2.5cm{\dotfill}&2y-y&=\hbox to 2.5cm{\dotfill}\cr 5y^2-2y^2&=\hbox to 2.5cm{\dotfill}&-2x^2-2x&=\hbox to 2.5cm{\dotfill}&3x-2x^2&=\hbox to 2.5cm{\dotfill}\cr }