Question

21.Dacă a+b=-27,c=-59,calculati c+(a+b).

22.Dacă a=-11,b+c=89,calculati c+a+b.

23.Daca a+b=-71,c+d=+26,calculati (a+b)+(d+c).

24.Daca a+c=-7,b+d=-35,calculati (a+b+c)+d.

25.Scrieți numărul a în două moduri:o dată ca sumă de două numere cu același semn și o data ca sumă de două numere cu semne diferite:
a)a=99
b)a=-205
c)a=-63
d)a=10
e)a=+567

Answer 1

Adunarea este comutativă.

21. a+b = -27
c= -59
c+ ( a+b ) = - 59 + ( - 27 ) = -59 - 27 = -86
22.
a=-11                                                                                                                             b+c = 89                                                                                                                  c+a+b = a + b+c = -11 + 89 = 78
23.                                                                                                                               a+b=-71                                                                                                                           c+d = 26
(a+b) + ( d+c ) = (a+b)+(c+d) = -71 + 26 = -45
24.                                                                                                                              a+c=-7                                                                                                                             b+d = -35
(a+b+c) +d = a+b+c+d = a+c+b+d = -7 + ( -35 ) = - 7 - 35 = -42
25.
a) a = 99
a=88+11=99                                                                                                                     a=100-1=99                                                                                                                                       
b) a = -205
a=-200-5=-205                                                                                                                 a=-210+5=-205                                                                                                                                       
c) a = -63
a = -50 - 13 = -63                                                                                                            a=-70+7=-63                                                                                                                                       
d) a = 10
a = 5 + 5 = 10
a=20-10=10                                                                                                                                      
e) a = 567
a = 500 + 67 = 567                                                                                                        a=600-33=567                                                                                                                                       
Vacanță plăcută în continuare! Spor la scris

Answer 2

21. a+b= -27,                 c+( a+ b) = - 59 + (-27)
          c= -59 
______________                          = - 59- 27
    c+(a+b) = ?
                                                      = - 86

22.    a= -11            c+ a+ b= a+ b+ c
     b+c= 89
__________                        = - 11+ 89
     c+a+b = ?
                                            = + 78

23. a+b= -71                      (a+b)+(d+c) = - 71+ 26
      c+d=+26
___________                                        = - 45
 (a+b)+(d+c) = ?

24. a+c= -7                 (a+b+c)+d= a+ b+ c+ d
      b+d=-35
__________                                = (a+ c)+ (b+ d)
  (a+b+c)+d=? 
                                                    = - 7+ (-35)

                                                    = - 7- 35

                                                    = - 42

25. S= aceleaşi semne;

      S = semne diferite

a. a= 99     +44+55 = +99;              +25+ (-134) = 99

b. a= -205   (- 123)+(-82) =-205      +300 +( -95) = 99

c. a= - 63     (- 549)+(-14) = - 63      + 1 + (- 64) = - 63

d. a= 10       + 8+ 2= 10                      +55 + (-45) = 10

e. a=+567    + 457+ 110= 567             + 568 + (- 1)?= + 567