Question

Va rog am nevoie urgent de ele ​

Answer 1

Exercițiul 1

${2}^{3} = 8$(c)

Exercițiul 2

a) 8

3. $2 \times 2.5 = 5$ (b)

4. $1.2 = \frac{12}{10}$ (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. ${1.2}^{2} - {0.5}^{2} = 1.44 - 0.25 = 1.19$

10. b + c = 2 => c = 2 - b

$({{2}^{a} })^{b} \times ({ {2}^{b} })^{c}$ = ${2}^{ab + bc}$ =

= ${2}^{b(a + c)}$

= ${2}^{b(2 + 2 - b)}$

= ${2}^{b(4 - b)}$

= ${2}^{4b - {b}^{2} }$

11.

2 + 4 + 6 + ... + 50 =

= 2 (1 + 2 + 3 +... + 25) =

= $2 \times \frac{25 \times 26}{2} = 25 \times 26 = 650$

12.

$\frac{a + a + 1+ a + 2}{3} = \frac{3a + 3}{3} = \frac{3(a + 1)}{3} = a + 1 = 7$

=> 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