Question

Daca a , b ,c sunt numere naturale astfel incat a+b+c=57 si 2a+b+2c =73, calculati (a+c)×( 5×a+2×b+5×c ).

Answer 1

a + b + c = 57

2 a + b + 2 c = 73

( a + b + c ) + ( a + c ) = 73

57 + ( a + c ) = 73

a + c = 73 - 57

a + c = 16

______________

5 × a + 2 × b + 5 × c =  162

= 2 × ( 2 × a + b + 2 × c ) + ( a + c ) =

= 2 × 73 + 16 =

= 146 + 16 =

= 162

______________________

( a + c ) × ( 5 × a + 2 × b + 5 × c ) = 2 592

=   16  ×   162 =

= 2 592