1/3*5+1/5*7+1/7*9+...+1/97*99
=1/3-1/5+1/5-1/7+1/7-1/9+...+1/97-1/99
=1/3-1/99
32/99
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Bình luận (0)
1/3*5+1/5*7+1/7*9+...+1/97*99
=1/3-1/5+1/5-1/7+1/7-1/9+...+1/97-1/99
=1/3-1/99
32/99
G= 1/1*3*5 +1/3*5*7+ 1/5*7*9+...+1/95*97*99
tinh
2+4+6+8+10+...+98+100
1+3+5+7+9+...+97+99
tinh 99-97+91-89...+7-5+3-1=
Bài 1 tính nhanh
a 3/3*5+3/5*7+3/7*9+...+3/97*99
b 3/1*4+3/4*7+3/7*10+...+3/100*103
tinh nhanh
1+2+3+4+5+6+7+8+9+10+....+90+91+92+93+94+95+96+97+98+99
1+3+5+7+9+.....+97+99=
A bằng bao nhiêu
A=1+3+5+7+9+.............+97+99
tinh nhanh
99-97+95-93+91-89+.....7-5+3-1
32x47+32-53+168+79+132
25/2+25/3-25/7/1/3+1/3-1/7
A=99-97+95-93+91-89+......+7-5+3-1 Tinh nhan bieu thuc tren