Răspuns:
Explicație pas cu pas:
10.
7056 = 2^4*3^2*7^2
√7056 = 2^2*3*7 = 84
P = 84 cm
triunghi echilateral = 3 laturi egale
L = P : 3 = 84 : 3 = 28 cm
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11.
3136 = 2^6*7^2
√3136 = 2^3*7 = 56
A = L^2
L = √A = √3136 = 56 cm
P patrat = 4*L = 4*56 = 224 cm
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12.
a + b = 87
a - b = 55
aduni cele doua relatii
2a = 87 + 55 = 142
a = 142 : 2 = 71
b = 87 - a = 87 - 71 = 16
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13.
a) 2x - 1 = -7
2x = -7 + 1 = -6
x = -6 : 2 = -3
b) 4x - 7 = -15
4x = -15 + 7 = -8
x = -8 : 4 = -2
c) -3x + 2 = -7
-3x = -7 - 2 = -9
x = -9 : (-3) = 3
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14.
A = 36π cm^2
A = πR^2
πR^2 = 36π
R^2 = 36
R = √36 = 6 cm
L = 2πR = 2*π*6 = 12π cm
D = 2R = 2*6 = 12 cm
