2.
100%-10%=90%
258.75:90%=258.75 ×100/90=287,5 lei
100%+25%=125%
287,5:125%=287,5 ×100/125=230 lei pret initial
3.
a=gaini
b=iepuri
a+b=20 b=20-a
2a+4b=70
a+2b=35
a+2(20-a)=35
a+40-2a=35
a=5 gaini
b=15 iepuri
E(x,y)=x²+y²+10x-6y+35 =(x²+10x+25)+(y²-6y+9)+1 =
=(x+5)²+(y-3)²+1
pentru minim expresie
(x+5)²=0 x+5=0 x=-5
(y-3)²=0 y-3=0 y=3
E(-5,3)=1
