Răspuns:
Explicație pas cu pas:
Testul 2
1.
a + b = 35
a - b = 7
2a = 35 + 7 = 42
a = 42 : 2 = 21
b = 35 - 21 = 14
a x b = 21 x 14 = 294
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2.
a) 215 (89 - 86 - 1) = 215 x 2 = 430
b) 324 (255 + 745) = 324 x 1000 = 324 000
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3.
50 x 52 - 50 x 48 = 50 x (52 - 48) =50 x 4 = 200
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4.
(3N - 7) : 11 - 2 = 5
(3N - 7) : 11 = 7
3N - 7 = 77
3N = 84
N = 28
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5.
{200 - [200 - (200 - 199)]} x 100
= [200 - (200 - 1)] x 100
= (200 - 199) x 100
= 1 x 100 = 100
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6.
ab - ba = 45
10a - b - 10b - a = 9a - 9b = 9(a - b) = 45
a - b = 5
a = 9; b = 4; 94 - 49 = 45
a = 8; b = 3; 83 - 38 = 45
a = 7; b = 2; 72 - 27 = 45
a = 6; b = 1; 61 - 16 = 45
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Testul 3.
1.
Nu se vede tot textul
2.
[(219 + 181) : 10 + 5(87 - 65)] *(140 : 20 - 2) =
= (400 : 10 + 5*22)*(7 - 2) = (40 + 110)*5 = 150*5 = 750
3.
a*b = 79
b*c = 49
b*(a - c) = b*a - b*c = 79 - 49 = 30
4.
2*(x + 7) - 14 = 28
2*(x + 7) = 14 + 28 = 42
x + 7 = 21
x = 14
