A=1/3+1/3^2+...+1/3^8
3A=1+1/3+...+1/3^7
3A-A=1+1/3+...+1/3^7-(1/3+1/3^2+...+1/3^8)
2A=1-1/3^8
2A=3^8-1/3^8
A=3^8-1/2.3^8
A=1/3+1/3^2+...+1/3^8
3A=1+1/3+...+1/3^7
3A-A=1+1/3+...+1/3^7-(1/3+1/3^2+...+1/3^8)
2A=1-1/3^8
2A=3^8-1/3^8
A=3^8-1/2.3^8
a) 4 3/8 + 5 2/3 b) 2 3/8 + 1 1/4 + 3 6/7
c) 2 3/8 - 1 1/4 + 5 1/3 d) (5/2 + 1/3) : ( 1 - 1/2)
e) (5/2 - 1/3) x 9/2 - 6/7
1) 1 3/4-1 3/8:(3/8+9/20)
2) 4 7/8-3 11/12:( 5/6+1 1/8)
3) 8 2/3 : ( 6 2/3-4 1/2)-2 37/51
7-(2x-1/3)^2=3
(2x+1/3)^2-3/8=1/8
12:[29-(x-2/3)^2]=3
(3x-1/2)^3+8/3=29/9-14/27
2(2x-1/3)^2+4/3=5/6+13/18
Tìm X
TÍNH:
a)-1-1/2.(1+2)-1/3.(1+2+3)-...-1/101.(1+2+3+...+101)
b) 1/77.7^4.11^2.(77)^4.(1/7^2)^8.(7^8)^3.(-11)^3:(7^15.11^8
c) 1:0.25.(1+1/4)^2+25.[1:(4/3)^2 : (5/4)^3] : [1:(-2/3)^3]
GIÚP MÌNH VỚI
bài 3:
a) x - 3/4 = 6 x 3/8 b) 7/8 : x = 3 - 1/2 c) x + 1/2 x 1/3 = 3/4
d) 3/2 x 4/5 - x = 2/3 e) X x 3 1/3 = 3 1/3 : 4 1/4 f) 5 2/3 : x = 3 2/3 - 2 1/2
tìm x
a) -1/8 = 3/x b) x/3 = 3/x c)3/4 . x = 1 và 1/2
d) x - 3/10 = 7/15 : 3/5 e) -4/7 - x = -8/3 . 3/7
f) 4/7 . x - 2/3 = 1/5 g) 2/3 + 1/3 : 3 x = 1/5
h) 2/9 - 7/8 x=1/3 j) (2 và 4/5 x - 50) : 2/3 = 51
4 và 3/8 + 5 và 2/3 =
2 và 3/8 + 1 và 1/4 + 3 và 6/7 =
2 và 3/8 - 1 và 1/4 + 5 và 1/3 =
so sánh 1+5+5^2+..+5^9/1+5+5^2+5^3+...+5^8 với 1+3+3^2+..+3^9/1+3+3^2+3^3+...+3^8
Chưng tỏ
a, S= 1/2^2+1/3^2+...+1/9^2
Chứng tỏ 2/5<S<8/9
b, 1/2-1/4+1/8-1/16+1/32-1/64<1/3
c, 1/3-2/3^2+3/3^3-4/3^4+...+99/3^99-100/3^100<3/16
B=1/3+1/3^2+1/3^3+1/3^4)*3^5+(1/3^5+1/3^6+1/3^7+1/3^8)*3^9+.....+(1/3^97+1/3^98+1/3^99+1/3^100)*3^101
C=(1/4-1)*(1/9-1)*(1/16-1)*..........*(1/81-1)*(1/100-1)
D=(1/2-1)(1/2+1)(1/2^2+1)(1/2^4+1)(1/2^8+1)(1/2^16+1)
Bạn nào làm đúng cả 3 câu này mình tick cho 3 cái