Đáp án: A=49/50 Giải thích các bước giải: A= 5/3+11/6+19/10+29/15+………+9899/4950 = ( 1+2/3)+( 1+ 5/6)+(1+9/10)+(1-14/15)+……+(1+4949/4950) = (1+1+1+…+1)+(2/3+5/6+9/10+14/15+…..+4949/4950) = (1+1+1+…+1)+[ (1-1/2)+(1-1/6)+(1-1/15)+…+(1-1/4950) ] = (1+1+1+…+1)+(1-1-1-…-1)+(1/1×2 + 1/2×3 + 1/3×5 +…+1/49×50) = 1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+…+1/49-1/50 = 1-1/50 = 49/50 Bình luận
Đáp án:
A=49/50
Giải thích các bước giải:
A= 5/3+11/6+19/10+29/15+………+9899/4950
= ( 1+2/3)+( 1+ 5/6)+(1+9/10)+(1-14/15)+……+(1+4949/4950)
= (1+1+1+…+1)+(2/3+5/6+9/10+14/15+…..+4949/4950)
= (1+1+1+…+1)+[ (1-1/2)+(1-1/6)+(1-1/15)+…+(1-1/4950) ]
= (1+1+1+…+1)+(1-1-1-…-1)+(1/1×2 + 1/2×3 + 1/3×5 +…+1/49×50)
= 1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+…+1/49-1/50
= 1-1/50
= 49/50