-9/46-4 1/23:(3 1/4 - x:3/5)+2 8/23=1
(6 2/7*x + 3/7):2 1/5-3/7=-1
5 8/17:x+(-1/17):x +3 1/17:17 1/3=4/17
Cho C = 1/3 + 1/3^2 + ....+ 1/20.CMR < 1/2
Bài 2 tìm x ϵ z
a)-4/3/5 . 2 /4 /23 ≤ x ≤ -2/2/5 : 1/6/15
b)-4/1/3 . ( 1/2 - 1/6) ≤ x ≤ -2/3 . ( 1/3 . 1/2 .3/4)
\(B=\dfrac{\left(\dfrac{11^2}{200}+0,415\right):0,01}{\dfrac{1}{12}-37,25+3\dfrac{1}{6}}\) tính B
tìm X
\(\dfrac{-9}{46}-4\dfrac{1}{23}:\left(3\dfrac{1}{4}-x:\dfrac{3}{5}\right)+2\dfrac{8}{23}=1\)
A=\(\dfrac{1}{2^2}+\dfrac{1}{3^2}+\dfrac{1}{4^2}+...+\dfrac{1}{n^2}\)
CMR: \(\dfrac{2}{5}< A< \dfrac{8}{9}\)
Tìm x E N , biết :
1/1.3+1/3.5+1/5.7+...+1+(5x+1.5x+3) =11/23
Cho A=1/22 + 1/32 + 1/42 + ... + 1/202
Chứng tỏ rằng A < 1
Bài 1:Thực hiện phép tính
a)\(\left(4\frac{4}{9}+3\frac{1}{3}\right).2\frac{1}{4}.2\frac{3}{4}\)
b)( 204,12 : 40,5 - 3,2 . 1.2 ) . \(6\frac{1}{2}\)
c)60% . \(\left(-\frac{5}{22}\right)+0,9:3\frac{2}{3}\)
a. 2/3x-1/2=1/10
b. 39/7:x=13
c. (14/5x-50):2/3=51
d. (x+1/2)(2/3-2x)=0
e. 2/3x-1/2x=5/12
g. (x.44/7+3/7)11/5-3/7=-2
h. x.13/4+(-7/6)x-5/3=5/12
i.93/17:x+(-4/17):x+22/7:52/3=4/11
j. 17/2-|2x-3/4|=-7/4
k. (x+1/5)^2+17/25=26/25
l. -32/27-(3x-7/9)^3=-24/27