2x - \(\dfrac{1}{2}-\dfrac{1}{6}-...-\dfrac{1}{49.50}\)= 6-\(\dfrac{1}{50}\) + x
<=> x - ( \(\dfrac{1}{1.2}+\dfrac{1}{2.3}+...+\dfrac{1}{49.50}\)) = \(\dfrac{299}{50}\)
<=> x - \(\left(1-\dfrac{1}{50}\right)\) = \(\dfrac{299}{50}\)
<=> x - \(\dfrac{49}{50}\) = \(\dfrac{299}{50}\)
<=> x = \(\dfrac{174}{25}\)
2x-1/2-1/6-1/12-....-1/49.50=7-1/50+x
2x-1/2-1/16-1/12-....-1/49.50=7-1/50+x
CMR:
a) \(\frac{1}{1.2}+\frac{1}{3.4}+\frac{1}{5.6}+...+\frac{1}{49.50}=\frac{1}{26}+\frac{1}{27}+\frac{1}{28}+...+\frac{1}{50}\)
b) Cho A = \(\frac{1}{1.2}+\frac{1}{3.4}+\frac{1}{5.6}+...+\frac{1}{99.100}\)
CMR: \(\frac{7}{12}< A< \frac{5}{6}\)
tìm x
a. \(\sqrt{x^6+1}\)= x^ 2
b. (2x+1)^5= (2x-1)^2011
c. 12-|x-3|=5x+8
d. 2. (1/4x-3) - 5/6. (6x-3/5) = -2
tim x y z
\(\dfrac{7x-3y+12}{2y}\) = \(\dfrac{y+2z}{z-y+2}\)= \(\dfrac{x}{-y}\)
help me soon^-^
CMR : \(\dfrac{1}{1.2}+\dfrac{1}{3.4}+...+\dfrac{1}{49.50}=\dfrac{1}{26}+\dfrac{1}{27}+...+\dfrac{1}{50}\)
tính: A=\([\dfrac{1\dfrac{11}{31}.4\dfrac{3}{7}-(15-6\dfrac{1}{3}.\dfrac{2}{19})}{4\dfrac{5}{6}+\dfrac{1}{6}(12-5\dfrac{1}{3})}.(-1\dfrac{14}{93})].\dfrac{31}{50}\)
Tìm các số hữu tỉ x trong các tỉ lệ thức:
a) 0,4: x=x:0,9
b) 0,2: hỗn số 1 và 1/5=2/3: (6x+7)
c) hỗn số 13 và 1/3: hỗn số 1 và 1/3=26: (2x+1)
d) x/3, 15=0, 15/7, 2
e) -2, 6/x=-12/42
f) x²/6=24/25
n) x-1/x+5=6/7
Help me
A=\(\dfrac{1}{1.2^2}+\dfrac{1}{2.3^2}+\dfrac{1}{3.4^2}+...+\dfrac{1}{49.50^2}\)
B=\(\dfrac{1}{2^2}+\dfrac{1}{3^2}+\dfrac{1}{4^2}+...+\dfrac{1}{50^2}\)
CM A<B
