ta tách : 1,5 * ( 2/3*5 +2/5*7+.........+2/47*49) 1,5*( 1/3-1/5+1/5-1/7 +.............+1/47-1/49) 1,5*( 1/3 -1/49) =1,5* 46/147=23/49
Tinh nhanh B=3/3*5+3/5*7+3/7*9+...+3/47*49
tính
14/5 -7/5=
7/8 -1/3+5/4
7/6+2/15+5/6+13/15
4/3*5/11
2/9:6*1/4
tính nhanh
3/4*4/5*5/6*6/7*7/9
22/3*1/6+1/6*2/3
9*1/3-2/5*1/3-3/5*1/3
mọi người giúp em với ạ
tính
C= 3/3*5+3/5*7+3/7*9+...+3/47*49
Tính nhanh s= 3 * 5 + 5*7 + 7*9 +.....+ 47*49
1+3+5+7+...+47+49+...+(-2)+(-4)+9(-6)+...+(-48)+(-50)
a)11/53+(32/47+-10/53)+-64/94+1/53+1/3
b) (-1+45/115+47/51)+(-9/23+-1/3)
c) -13/49+12/48+1/12+3/18
d) 13/15+(-4/5+7/18)+-5/12+1/16
A=1/1*2+1/1*3+1/3*5+1/5*7+...+1/47*49
tinh nhanh (viet ho minh luon cach lam nha)
a=1-3+5-7+9 -11+...+49-51
b=-1+4-5+8-9+12-...-53+56
c=1+3-5-7+9+11-...-397-399
d=1-2-3+4+5-6-7+...+97-98-99+100
Bài 9: Tính nhanh
a) 99 - 97 + 95 - 93 + 91 - 89 + ..... + 7 - 5 + 3 - 1
b) 50 - 49 + 48 - 47 + 46 - 45 + ..... + 4 - 3 + 2 -1