`a) (-2+1/2):(4/5-1/2)`
`= -3/2 :3/10`
`= -3/2 . 10/3`
`=-5`
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Bài 1
a, Tính P=1+1/2(1+2)+1/3(1+2+3)+1/4(1+2+3+4)+....+1/2012(1+2+3+...+2012)
b,Tìm x thỏa mãn 4^5+4^5+4^5+4^5/3^5+3^5+3^5.6^5+6^5+6^5+6^5+6^5+6^5/2^5+2^5=2^x
a) A= 1/3 – 3/4 – (-3/5) + 1/15 – 2/9 – 1/36 b) 2/5 + (-4/3) - 1/2 c) 1/3 – [( -5/4) – (1/4 + 3/8)]
a)-1/24-[1/4-(1/2-7/8)]
b)(5/7-7/5)-[-1/2-(-2/7-1/10)
c)(-1/2)-(-3/5)+(-1/9)+1/71-(-2/7)+4/35-7/18
d) (3-1/4+2/3) -(5-1/3-6/5)-(6-7/4+3/2)
Tính A = 1/2-2/3-2/3+1/4+2/4+3/4-1/5-2/5-3/5-4/5+...+1/10+2/10+3/10+...+9/10. HELP ME!
a,(3/7+1/2)2 b, (3/4-5/6)2 c,54.204 /255.45 d,(-105/3).(-64/5)
e,(1+2/3-1/4).(4/5-3/4)2 f 2:(1/2-2/3)3
a) Rút gọn biểu thức sau:
A=2*2^2+3*2^3+4*2^4+5*2^5+...+100*2^100
b) Cho B=1/2-1/3+1/4-1/5+...+1/98-1/99
CMR: 0,2< B < 0,4
Bài 1. Tìm x, biết:
a/ 1/4.(x-3)+2=1/5
b/ 1/7-2.(x+1)=1/4+2/3
c/ 1/4.(2x+3)-1/9=2/5
d/ 3/2.(x+1)-4/9=2/3
e/ 4/5.(2-3x)+4/7=2và1/3
[Cần gấp ạ!]
chứng minh A=B :
B= 1.2:(1/1/5*1/1/4) trên 0.32+2/25
A=(3 /2/15 + 1/5 ) : 2/1/2 tren (5/3/7 - 2/1/4):4/43/56
Bài 1: CMR 3/1^2*2^2 + 5/2^2*3^2 + 7/3^2*4^2 + ....... + 19/9^2*10^2 bé hơn 1
Bài 2: CMR 1/3 + 2/3^2 Bài 1: CMR 3/1^2*2^2 + 5/2^2*3^2 + 7/3^2*4^2 + ....... + 19/9^2*10^2 bé hơn 3/4
Bài 3: Cho A= 1/1*2 + 1/3*4 + 1/5*6 + .... + 1/99*100. CMR 7/12 < A < 5/6
a) (2/3 + 1/5)²: (2/5 - 1/3)
b) (2va 1/3 - 1va 3/5) * (2va 4/9: 3 va 1/2)²
c) (2/3 + 1/4 - 2/5): (4/5 -3/7)