Question

Stiind ca a = 1 supra 1+2+3+...+10 si b = 1 supra 1+2+3+...+11 calculati: a) b^-1; b) a:b; c) -11(a-b); d)22*(5a-6b).

Answer 1

Răspuns:

Explicație pas cu pas:

1+2+3+...+10 = 10*11/2 = 55

a = 1/55

1+2+3+...+11 = 11*12/2 = 66

___________

a = 1/55

b = 1/66

b^-1 = 1/b = 1/(1/66) = 66

a : b = 1/55 : 1/66 = 1/55*66/1 = 66/55 = 6/5

-11(a - b) = -11(1/55 - 1/66) = -11*(6/11*5*6 - 5/11*5*6) = -11*1/11*5*6 = -1/30

22*(5a - 6b) = 22*(5/55 - 6/66) = 22*(1/11 - 1/11) = 0