\(\frac{3}{1x3}+\frac{3}{3x5}+...+\frac{3}{49x51}=\frac{3}{2}\left(\frac{2}{1x3}+\frac{2}{3x5}+...+\frac{2}{49x51}\right)=\frac{3}{2}\left(\frac{1}{1}-\frac{1}{3}+...+\frac{1}{49}-\frac{1}{51}\right)\)
\(=\frac{3}{2}.\frac{50}{51}=\frac{25}{17}\)
1x3/3x5 + 2x4/5x7 + 3x5/7x9 + ............... +49x51/99x101
1x3/3x5 + 2x3/5x7 + 3x5/7x9 + ............... +49x51/99x101
A = 4/1x3+16/3x5+36/5x7+...+2500/49x51
tính tổng của A
Tính nhanh :
3 / 1x3 + 3 / 3x5 + 3 / 5x7 +.............+ 3 / 2017x2019
Câu 1:Tính nhanh:
3/1x3+3/3x5+3/5x7+3/7x9+...+3/49x51
Câu 2:Tìm các chữ số a,b,c sao cho a,b x a,b =c,ab.
Nhanh thì mình
Sẽ cho tick
tính bằng cách hợp lí
3/1x3 + 3/3x5 + 3/5x7 +.....+3/97x99
a)1/1x3+1/3x5+1/5x7+...+1/Xx(x+3)=99/200
b)1/1x3+1/3x5+1/5x7+...+1/Xx(x+2)
Tính nhanh
A=3/1x3+3/3x5+3/5x7+3/7x9+...+3/99x97
B=1/15+1/35+1/65+...+1/4443+1/599
C=1/1x2x3 +1/2x3x4 +1/3x4x5 +... +1/50x51x52
Tính nhanh
M = 3/1x3 + 3/3x5 + 3/5x7 + ... + 3/45x47 + 3/47x49
N = 5/1x5 + 5/5x9 + 5/9x13 + ... + 5/97 x 101 + 5/101x105
Các bạn giúp mình nhé
