Question

16. si 19. . Numai subpunctele incercuite (coroana)

Answer 1

Explicație pas cu pas:

b)S=1/6·7+1/7·8+1/8·9+...+1/74·75

S=1/6-1/7+1/7-1/8+1/8-1/9+...+1/73-1/74+1/74-1/75

dupa cum observam termenii se reduc si ramane :

1/6-1/75=75/450-6/450=69/450

c)S=1/4·5+1/5·6+1/6·7+...+1/71·72

S=1/4-1/5+1/5-1/6+...+1/71-1/72

S=1/4-1/72

S=18/72-1/72

S=17/72

a)

S=2/1·3+2/3·5+2/5·7+...+2/97·99

S=2/1-2/3+2/3-2/5+2/5-2/7+...+2/97-2/99

S=2/1-2/99

S=198/99-2/99

S=196/99