(5x-6).y=70
Tìm x biết
10 + 2 . x = 4⁵ : 4³
2 x - 6² : 18 = 3.2²
70 - 5 . ( x- 3 ) = 3.2
1)17-2 (2x-3)=3 2)125-5 (3x-1)=25
3)70-5(2x-3)=45 4)231-(x-6)=133:13
5)2448 : [119- (x-6)]=24 6)15x-13x=882
7)[ (6x-72):2-84].28=5628 8)100-4(30-5x)=20
Tìm x :
a) 13 - 2 ( x + 1 ) = 7
b) 6x + 2 . 4 = 5^2 . 2
c) 420 + 65 . 4 = ( x + 175 ) : 5 + 30
d) 32 . 12 : 2 = ( x + 70 ) : 14 - 40
e) 231 - ( x - 6 ) = 1339 : 13
f) 10 + 2x = 4^5 : 4
g) 70 - 5 ( x - 3 ) = 45
\(\dfrac{4}{6}+\dfrac{4}{30}+\dfrac{4}{70}+\dfrac{4}{126}+...+\dfrac{4}{1350}\)
Bài 1: Tính nhanh;
A = 6/4 + 6/28 + 6/70 + 6/130 + 6/208
\(\dfrac{1}{2}.\)\(\dfrac{3}{5}+\dfrac{4}{7}:\dfrac{4}{5}-\dfrac{1}{70}\)
\(\left(\dfrac{2}{3}+\dfrac{1}{5}-\dfrac{4}{9}\right):\left(\dfrac{1}{3}+\dfrac{2}{5}-\dfrac{6}{9}\right)\)
tĩm x:
1) (32 +1). x +5x . 32 - 10=102
2) 2.4x=32
3)670 . 6x= 689
4)7200 . 7x = 7300
5) 15<2x<65
6)16 < hoặc bằng 4x< hoặc bằng 256
chứng minh
a) 1/6<1/5^2+1/6^2+1/7^2+......+1/100^2 < 1/4
b) 4/3<1/11+1/12+....+1/70<5/2