Question

va rog mult. merciiiiiii

Answer 1

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Answer 2

16)

a)  - 7 + ( - 5 + 5 ) = - 7 + 0 = - 7

b)  - 4 + ( 4 - 8 ) = - 4 + ( - 4 ) = - 4 - 4 = - 8

c)  - 4 509 + 2 315 + 4 509 = ( - 4 509 + 4 509 ) + 2 315 = 0 + 2 315 = 2 315

d )  123 - ( 117 - 0 ) + ( - 123 ) + 118 =  ( 123 - 123 ) - 117 + 118 = 0 + 1 = 1

e)  135 - 143 - ( 135 - 143 ) + 1 = - 1 - ( - 1) + 1 = - 1 + 1  + 1 =0 + 1 = 1

f)   - 6 - [ 2 + ( - 8 ) + 0 ] = - 6 - ( 2 - 8 ) = - 6 - ( - 6 ) = - 6 + 6 = 0

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17) - 100 - 99 - 98 - 97 - ........ - 1 + 0 + 1 + 2 + 3 + ......... + 101 + 102 =  203

=  ( - 100 + 100 ) + ( - 99 + 99 ) + .......... ( - 1 + 1 ) + 0 + 101 + 102 =

=  0 + 0 + ...... + 0 + 203 =

= 203

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19)

            7       ⇔   [ 12 + ( - 5 ) = 12 - 7 = 5 ]

      12    - 5    ⇔  [  2 + 10 = 12;   10 + ( - 15 ) = 10 - 15 = - 5 ]

   2    10   - 15  ⇔  [ - 5 + 7 = 2;   7 + 3 = 10;   3 + ( - 18 ) = 3 - 18 = - 15 ]

- 5   7    3    - 18  → numerele de la baza piramidei

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20)   a)    ( - 3) × ( + 4 ) = - 12

b)  ( - 21 ) ×  ( - 5 ) = + 105

c)    2 × ( - 3 ) = - 6

d )  ( - 3 ) × 47 = - 141

e)   - 7 × 315 × 0 = 0 → daca intr -un produs , un factor este 0, atunci produsul e 0

f)   ( - 21 ) × 1 × ( - 1 ) = + 21 ;   ( - ) × ( - ) = +

g)   - 10 × ( - 3 / 7 ) = + 30 / 7

h )   - 20 × 173 × ( - 5 ) = + 17 300

i )   ( - 5 ) × ( - 115 ) × ( - 20 ) = - 11 500

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21 )

a) produsul  sa fie - 1

 1      1       - 1  →  1 × 1 × ( - 1 ) = - 1

- 1       1       1  →  ( - 1 ) × 1 × 1 = - 1

  1    - 1       1  →  1 × ( - 1 ) × 1 = - 1

 ↓       ↓      ↓

- 1       - 1    - 1

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b)   produsul sa fie 1

1    - 1     - 1  →  1  × ( - 1 ) × ( - 1 ) = 1

1      1        1  →  1 × 1 × 1 = 1

1     - 1     - 1  →  1 × ( - 1 ) × ( - 1 ) = 1

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22 ) a )   - 5 × 3 + 10 = - 15 + 10 = - 5

b)  - 5 × ( - 7 ) + ( - 5 ) × 3 = ( - 5 ) × ( - 7 + 3 ) = ( - 5 ) × ( - 4 ) = + 20

c)   - 5 × ( - 7 + 3 ) = - 5 × ( - 4 ) = + 20

d )    - 8 × 6 + ( - 8 ) × ( - 7 ) = - 48 + 56 = 8

e )    12 + ( - 12 ) × 35 + 12 × 34 = 12 × ( 1 - 35 + 34 ) = 12 × 0 = 12

f)   3 ×  ( 1 + 2 + 3 + ........ + 1 000 ) + ( 3 + 4 + 5 + ........... + 1 000 ) × ( - 3 ) = 9

= 3 × 1 000 × 1001 / 2 +( - 3 ) ×  ( 1 000 - 3 + 1 ) termeni ×  1 003 / 2 =

= 3 × 500 × 1001  - 3 × 499 × 1 003 =

= 3 × ( 500 500 - 500 497  )  = → l-am dat factor comun pe 3

= 3 × 3 =

= 9