\(B=\frac{2}{3.5}+\frac{2}{5.7}+......+\frac{2}{29.31}\)
\(B=2.\left(\frac{1}{3.5}+\frac{1}{5.7}+....+\frac{1}{29.31}\right)\)
\(B=2.\left(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+.....+\frac{1}{29}-\frac{1}{31}\right)\)
\(B=2.\left(\frac{1}{3}-\frac{1}{31}\right)\)
\(B=2.\frac{28}{93}\)
\(B=\frac{56}{93}\)
k cho mình nha chúc bạn học tốt
A=1/3+1/6+1/10+1/15+...+1/66
B= 2/15+2/35+2/63+..+2/399
A=\(\dfrac{2}{15}\)+\(\dfrac{2}{35}\)+\(\dfrac{2}{63}\)+...+\(\dfrac{2}{399}\)
tính hợp lí:
2/15+2/35+2/63+......+2/399
A=\(\frac{2}{15}+\frac{2}{35}+\frac{2}{63}+...+\frac{2}{399}\)
a) A= 4/3.7 + 4/7.11 + 4/11.15 +...+ 4/107.111
b) B= 2/15 + 2/35 +2/63+...+ 2/399
c) C= 1/10 + 1/15 + 1/21+ ...+ 1/120
Tính tổng:
D=3-32-33-..........-3100
B=-2/15-2/35-2/63-..........-2/399
CẦN GẤP NHÉ MỌI NGƯỜI
Bài 1: tính
A=2/15 +2/35 + 2/63 +.......+ 2/399
B=2/15+2/35+2/63+....+2/399
c=7/10.11+7/11.12+7/12.13 + .....+7/69.70
D=6/15.18 + 6/ 18.21+6/21.24 +...+6/87.90
