1)20% din 190= 20/100*90=1/5*90=18
190+18=208
208-x/100*208=193,80
208-2,08x=193,80
-2,08x=193,80-208
-2,08x=-14,2
2,08x=14,2
x=6,82%
3)35+3*35=35+105=140
4)a/b=4/10=2/5
a/b=2/5 a=2b/5
a+b=84
2b/5+b=84 aducem la acelasi numitor
2b+5b=420
7b=420
b=60 a=24
5)E(x)=(3x+1)³-4(3x+1)=(3x+1)[(3x+1)²-4]=(3x+1)(3x+1-2)(3x+1+2)=(3x+1)(3x-1)(3x+3)
S2)
1)P ABCED=20*5=100
100:4=25-braduti
25*140=3500
25:7=3,4 deci trei braduti sunt gratis
3*140=420
3500-420=3080-trebuie sa se plateasca pentru braduti
2)Al=Pb*h=3*4√3*6=72√3
At=Al+2Ab
Ab=l²√3/4=(4√3)²*√3/4=48√3/4=12√3
At=72√3+2*12√3=72√3+24√3=96√3
V=Ab*h=12√3*6=72√3