Question

4 caiete si 2 stilouri costa impreuna 32 lei , iar 2 caiete si 6 stilouri costa 66 de lei .
Cat costa un caiet si cat costa un stilou?
Cu METODA COMPARATIEI !!!!!!!!!!!!!! URGENT!!!!!!!!!!!!!!

Answer 1

[tex] \left \{ {{4a+2b=32|*(+1)\ \textless \ =\ \textgreater \ 4a+2b=32} \atop {2a+6b=66|*(-2)\ \textless \ =\ \textgreater \ -4a-12b=-132}} \right. \\ -----------\\ -10b=-100=\ \textgreater \ b=-100:(-10)=\ \textgreater \ b=10\\ 4a+2*10=32=\ \textgreater \ 4a+20=32=\ \textgreater \ 4a=12=\ \textgreater \ a=12:4=\ \textgreater \ a=3\\\\ Proba:4*3+2*10=32\\ 12+20=32\\ 32=32\\\\ 2*3+6*10=66\\ 6+60=66\\ 66=66 [/tex] [tex]Metoda~II:metoda~comparatiei\\ 4a+2b=32\\ 2a+6b=66\\ 4a.......2b........32\\ 2a.......6b.......66\\ Daca~luam~cantitati~duble,a dica~inmultim~cu~2~cantitatile\\ celui~de~al~doilea~rand~pretul~se~dubleza~si~avem:\\ 4a........2b.......32lei\\ 4.a.......12b......132lei\\ 12-2=132-32=\ \textgreater \ 10stilouri=100lei=\ \textgreater \ 1stilou=10lei\\ 4a+2*10=32=\ \textgreater \ 4a+20=32=\ \textgreater \ 4a=12=\ \textgreater \ a=12:4=\ \textgreater \ a=3\\ deci~un~pix~=3lei~si~un~stilou~10~lei.[/tex]