Răspuns:
Explicație pas cu pas:
15.
P1 = L x 4
dupa marirea laturii
P2 = (L + 1,5) x 4 = 4L + 6 cm = P1 + 6 cm
periemtrul se mareste cu 6 cm
16.
P = 2 x (L + l)
L + l = P : 2 = 36 : 2 = 18 cm
l = 18 - L = 18 - 10 = 8 cm
17.
P = 2 x (L + l)
L + l = P : 2 = 34 : 2 = 17 cm
L = l + 5
l + 5 + l = 17
2l = 17 - 5 = 12
l = 12 : 2 = 6 cm
L = 6 + 5 = 11 cm
18.
P = 2 x (L + l)
L + l = 22,2 : 2 = 11,1 cm
l = L - 3,9
L + L - 3,9 = 11,1
2L = 11,1 + 3,9 = 15
L = 15 : 2 = 7,5 cm
l = 7,5 - 3,9 = 3,6 cm
19.
L + l = 34 : 2 = 17 cm
L = 4l
4l + l = 17
5l = 17
l = 17: 5 = 3,4 cm
L = 17 - 3,4 = 13,6 cm
Răspuns:
15) P₁=4L
L+1,5 → latura marita
P₂=4(L+1,5)=4L+6
P₂-P₁=4L-4L+6=6cm mai mare
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16) P=2(L+l)
L=10cm
36=2(10+l)
36:2=10+l
18-10=l=>l=8cm latimea
___________________
17) P=34cm
L=l+5
34=2(l+5+l)
34:2=2l+5
17-5=2l=>l=12:2=>l=6cm latimea
L=6+5=11cm lungimea
________________
18) P=22,2cm
l=L-3,9
22,2=2(L+L-3,9)
22,2:2=2L-3,9
11,1+3,9=2L=>L=15:2=>L=7,5cm lungimea
l=7,5-3,9=3,6cm latimea
________________
19) P=34cm
L=4l
34=2(4l+l)
34:2=5l=>l=17:5=>l=3,4cm latimea
L=4·3,4=>L=13,6cm lungimea
