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5/1+5/2+5/3+......+5/30=?​

Răspuns :

Răspuns:

(5/1+5/2+5/3+......+5/30=?​) :(9/2+9/4+....+9/60)=???

10/9

Explicație pas cu pas:

5(1+1/2+1/3+...+1/30) :[(9/2) (1+1/2_..+1/30)

fie 1+1/2+1/3+...+1/30=a

atunci

5a: 9a/2=5*2/9=10/9

5(1+1/2+1/3+...+1/30)=x ¦^-1

1/5(1+2+3+...+30)=1/x

1/5 × 30×31/2=1/x

3×31=1/x

93=1/x=>x=1/93