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Daca a+3b=7,3b+2c=9,c+d=1.aflati valoarea expresiei 2a+15b+10c+4d

Răspuns :

Spidie

a+3b=7,3b+2c=9,c+d=1

2a+15b+10c+4d = (2a+6b) +( 9b+6c)+ (4c+4d)=2*(a+3b)+3*(3b+2c)+(c+d)=

=2*7+3*9+1=14+27+1=42

Milumil2000
a+3b=7
3b+2c=9
c+d=1

 2a+15b+10c+4d=2(a+3b)+3(3b+2c)+4(c+d)=2x7+3x9+4x1=14+27+4=55