Question

Calculeaza'(11+22+55...+99):(1+2+3...+9)=
REZOLVA URMATOARELE CERINTE afla nr a daca ab+ac=520,b+c=52
afla nr a daca ab-ac=45 si b-c=9
afla suma b+c daca ab+ac+70=120 si a=25
afla diferenta b-c daca ab-ac-48=2 si a=10

Answer 1

(11+22+55...+99):(1+2+3...+9)= 
11(1+2+5+...+9):(9x10:2)=
11x45:45=11

ab+ac=520,b+c=52 
a(b+c)=520
ax52=520
a=520:52
a=10

afla nr a daca ab-ac=45 si b-c=9 
a(b-c)=45
ax9=45
a=45:9
a=5

afla suma b+c daca ab+ac+70=120 si a=25 
a(b+c)+70=120
25(b+c)+70=120
25(b+c)=120-70
25(b+c)=50
b+c=50:25
b+c=2

afla diferenta b-c daca ab-ac-48=2 si a=10
a(b-c)-48=2
10(b-c)=2+48
10(b-c)=50
b-c=50:10
b-c=5

Succes !

Answer 2

11*(1+2+3+...9):(1+2+3...+9)=11*1

ab+ac=520,b+c=52 
a(b+c)=520, a*52=520 =>a=10

 ab-ac=45 si b-c=9 
a(b-c)=5, a*9=45 => a=5

ab+ac+70=120 si a=25 
a(b+c)=120-70
25(b+c)=50 => b+c=2

ab-ac-48=2 si a=10
a(b-c)=2+48
10(b-c)=50 => b-c=5