daca a+b=4 si c=5 calculeaza [4a+c+4b)*(3c-(2a+2b)]

Răspuns :

a+b=4 si c=5

 [4a+c+4b)
×(3c-(2a+2b)]= [4(a+b)+c)*(3c-2(a+b)]= (4×4+5)×(3×5-2×4)=
=(16+5)×(15-8)=21×7=147

[(4a+c+4b) x (3c-(2a+2b)] = 
[( 4(a+b) + c)  x ( 3c - 2(a+b)] =
[( 4 x 4 + 5 ) x ( 3 x 5 - 2 x 4)]=
[ ( 16 + 5) x ( 15 - 8 )]=
21 x 7 = 147