Question

Calculati in doua moduri:
a) 3/5•(1/9+4/9);
b) 2/3•(1/6+5/24);
c)1/7•(7/15-3/10);

Answer 1

a) 3/5 * (1/9 + 4/9)
1/9 + 4/9 = 5/9
3/5 * 5/9 = 15/45 = 1/3  = 0,(3)
Al doilea mod:
0,6 * [(0,(1) + 0,(4)] = 0,6,* 0,(5) = 0,(3) 

b) 2/3 * (1/6 + 5/24)
1/6 + 5/24 = 4/24 + 5/24 = 9/24 = 1/3
2/3 * 1/3 = 2/9   = 0,(2)
Al doilea mod:
0,(6) * [0,1(6) + 0,2)]  = 0,(6) * 0,3(6) = 0,2

c) Paranteza 7/15 - 3/10 = 35/150 = 7/30  
1/7 * 7/30 = 7/210 = 1/30  sau  0,0(3)
Al doilea mod:
0,14 * 0,2(3) = 0,03
Multa bafta