Explicație pas cu pas:
Ex. 11
a)2*l=L
P=2×(l+L)=2×(l+2l)=6l=300m=> l=50 si L=100
b) l=50m×2,5=55 m
L=100+5=105m
P=2×(55+105)=2×160=320m
c) A=2×2,5×105+2×2,5×50=5×(105+50)=5*155=775 m^2
Ex.10
a) l=4cm
L=4×2
L=8
P=(2×4)+(2×8)
P=8+16
P=24cm
b)
P=36cm
L=3×l
36=2×2l+2×3l
36=10l
l=36:10
l=3,6cm
L=3×3,6
L=10,8cm
Ex.9
a)1,2^2=1,44
b)0,2^3=0,008
c)0,144×10^2=2,4
d) 0,2:0,25=0,8
Ex.8
4,6+(12,2×2)=4,6+24,4=29 b)29
