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Stund ca a+b=14 si b+c= 9 calculati: a) 2×a+5×b+3×c=


Răspuns :

2×a+5×b+3×c=

2×a+2×b+3×b+3×c=

2×(a+b)+3×(b+c)=

2×14+3×9=

28+27=

=55

Răspuns:

a+b=14 |×2

2a+2b=28

b+c=9 |×3

3b+3c=27

2a+5b+3c

5b=2b+3b

2a+2b+3b+3c=28+27=55