Exercițiul 1
[tex] {2}^{3} = 8[/tex](c)
Exercițiul 2
a) 8
3. [tex]2 \times 2.5 = 5[/tex] (b)
4. [tex]1.2 = \frac{12}{10} [/tex] (a)
5. 2x - 5 = 11
=> 2x = 16
=> x = 8 (a)
6. Aria dreptunghiului = L * l = 9 * 6 = 54 cm^2 (b)
7. 1 decemetru = 0,1 m
=> 7 decemetri = 0,1 * 7 = 0,7 m (b)
8. d) 7, 21
Subiect II
9. [tex] {1.2}^{2} - {0.5}^{2} = 1.44 - 0.25 = 1.19[/tex]
10. b + c = 2 => c = 2 - b
[tex] ({{2}^{a} })^{b} \times ({ {2}^{b} })^{c} [/tex] = [tex] {2}^{ab + bc} [/tex] =
= [tex] {2}^{b(a + c)} [/tex]
= [tex] {2}^{b(2 + 2 - b)} [/tex]
= [tex] {2}^{b(4 - b)} [/tex]
= [tex] {2}^{4b - {b}^{2} } [/tex]
11.
2 + 4 + 6 + ... + 50 =
= 2 (1 + 2 + 3 +... + 25) =
= [tex]2 \times \frac{25 \times 26}{2} = 25 \times 26 = 650[/tex]
12.
[tex] \frac{a + a + 1+ a + 2}{3} = \frac{3a + 3}{3} = \frac{3(a + 1)}{3} = a + 1 = 7[/tex]
=> a = 6
=> numerele sunt 6, 7, 8.
13.
a - b = 18 => a = b + 18 }
} => b + 18 = 3b + 2 =>
a : b = 3 r2 => a = 3b + 2 }
=> 3b - b = 18 - 2 => 2b = 16 => b = 8
=> a = 8 + 18 => a = 26
