Question

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Answer 1

Răspuns:

S1 = 1224 , S2 = 6324 , S3 = 855

Explicație pas cu pas:

S1= $(5*0-1)-(5*1-1)+(5*2-1)-(5*3-1)+...+(5*50-1) =$

S2= $(5*0-1)+(5*1-1)+(5*2-1)+...+(5*50-1)=$

$-1+4+9+14+19+24+29+34+39+44+49+54+59+64+69+74+79+84+89+94+99+104+109+114+119+124+129+134+139+144+149+154+159+164+169+174+179+184+189+194+199+204+209+214+219+224+229+234+239+244+249 = 6324$

S3=

$(5*2^0-1)-(5*2^1-1)+(5*2^2-1)-(5*2^3-1)+...+(5*2^9-1)= (5*1-1)-(5*2-1)+(5*4-1)-(5*8-1)+...+(5*512-1)= 4-9+19-39+79-159+319-639+1280= (-5)+(-20)+(-80)+(-320)+1280= (-25)+(-400)+1280= (-425)+1280= 855$

la prima suma nu am mai scris ca pt ca este 1 noaptea =]] dar te iei tu dupa a doua suma. Bafta!