Question

Chứng minh rằng: 1/26+1/27+1/28+...+1/50=1-1/2+1/3+1/4+...+1/49-1/50

Answer 1

 1/26+1/27+1/28+...+1/49+1/50=1-1/2+1/3-1... 
<=>2/26+2/28+2/30+...+2/50=1-1/2+1/3-1... 
<=>1/13+1/14+1/15+...+1/25=1-1/2+1/3-1... 
<=>2/14+2/16+2/18+...2/24=1-1/2+1/3-1/... 
<=>1/7+1/8+1/9+...+1/12=1-1/2+1/3-1/4+... 
<=>2/8+2/10+2/12=1-1/2+1/3-1/4+1/5-1/6 
<=>1/4+1/5+1/6=1-1/2+1/3-1/4+1/5-1/6 
<=>2/4+2/6=1-1/2+1/3 
<=>1/2+1/3=1-1/2+1/3 
<=>2/2=1

 

Answer 2

\(1-\frac{1}{2}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{49}-\frac{1}{50}=\left(1+\frac{1}{3}+\frac{1}{5}+...+\frac{1}{49}\right)-\left(\frac{1}{2}+\frac{1}{4}+...+\frac{1}{50}\right)\)

\(=\left(1+\frac{1}{2}+\frac{1}{3}+...+\frac{1}{50}\right)-2\left(\frac{1}{2}+\frac{1}{4}+...+\frac{1}{50}\right)=\left(1+\frac{1}{2}+\frac{1}{3}+...+\frac{1}{50}\right)-\left(1+\frac{1}{2}+\frac{1}{3}+...+\frac{1}{25}\right)\)\(=\frac{1}{26}+\frac{1}{27}+...+\frac{1}{50}\)

=>đpcm

Answer 3

nguyen thieu cong thanh z kết quả cúi cùng là ???

Answer 4

co hoi dap an dau, CM ma

 

Answer 5

bạn  nguyen thieu cong thanh đúng rồi chuẩn ko cần chỉnh cmmnr :)

Answer 6

Ta biến đổi vế phải :

1-1/2+1/3-1/4+.....+1/49-1/50

=(1+1/3+1/5+....+1/49)-(1/2+1/4+1/6+.......+1/50)

=(1+1/2+1/3+.....+1/49+1/50)-2(1/2+1/4+1/6+......+1/50)

=(1+1/2+...+1/50)-(1+1/2+1/3+....+1/25)

=1/26+1/27+.......+1/50

Vậy 1/26+1/27+1/28+.....+1/50=1-1/2+1/3-1/4+......+1/49-1/50

Mình không bấm phân số được mong mấy bạn thông cảm

Answer 7

1/26+1/27+1/28+...+1/49+1/50=1-1/2+1/3-1... 
<=>2/26+2/28+2/30+...+2/50=1-1/2+1/3-1... 
<=>1/13+1/14+1/15+...+1/25=1-1/2+1/3-1... 
<=>2/14+2/16+2/18+...2/24=1-1/2+1/3-1/... 
<=>1/7+1/8+1/9+...+1/12=1-1/2+1/3-1/4+... 
<=>2/8+2/10+2/12=1-1/2+1/3-1/4+1/5-1/6 
<=>1/4+1/5+1/6=1-1/2+1/3-1/4+1/5-1/6 
<=>2/4+2/6=1-1/2+1/3 
<=>1/2+1/3=1-1/2+1/3 
<=>2/2=1

Answer 8

cm mà các bạn

Answer 9

1/28+(-1)/14+3/28+(-1)/7+3/14 tính nhanh