a) A= \(\dfrac{1}{3}-\dfrac{3}{4}-\left(-\dfrac{3}{5}\right)+\dfrac{1}{72}-\dfrac{2}{9}-\dfrac{1}{36}+\dfrac{1}{15}\)

b) B=\(\dfrac{1}{5}-\dfrac{3}{7}+\dfrac{5}{9}-\dfrac{2}{9}+\dfrac{7}{13}-\dfrac{2}{11}-\dfrac{5}{9}+\dfrac{3}{7}-\dfrac{1}{5}\)

c) C=\(\dfrac{1}{100}-\dfrac{1}{100.99}-\dfrac{1}{99.98}-\dfrac{1}{98.97}--..-\dfrac{1}{3.2}-\dfrac{1}{2.1}\)

2. Tìm x, biết

a) \(\dfrac{-1}{4}\)-\(\dfrac{3}{4}\):x =\(\dfrac{-11}{36}\)

b) \(70\): \(\dfrac{4x+720}{x}\)=\(\dfrac{1}{2}\)

Giúp mình với

tính giá trị biểu thức

9.(\(\dfrac{1}{3}\))2-20140

giúp mk nha mk đang cần gấp

\(\left[\dfrac{3}{7}.\dfrac{4}{15}+\dfrac{1}{3}.\left(9^{15}\right)\right]^0.\dfrac{1}{3}.\dfrac{68}{124}\)

Tìm x, y\(\in\)Z, biết:

a) \(\dfrac{5}{x}+\dfrac{y}{4}=\dfrac{1}{8}\)

b) \(\dfrac{1}{x}=\dfrac{1}{6}+\dfrac{y}{3}\)

c) \((x+1)(x-2)<0\)

d) \((x-2)(x+\dfrac{2}{3})>0\)

a)1/6x + 1/10x - 4/15x + 1=0
b)(1/7x - 2/7)(-1/5x + 3/5)(1/3x + 4/3)=0
c)(x - 1/3)(y - 1/2)(z - 5)=0 và x + 2=y + 1=z + 3

1) Tìm x , y :

a) \(\dfrac{2}{3}\) x . ( x - 8 ) = 0

HELP ME

1) Chứng minh: \(\dfrac{1}{n+\left(n+1\right)}=\dfrac{1}{n}-\dfrac{1}{n+1}\)

2) Áp dụng tính tổng: A= \(\dfrac{1}{1.2}+\dfrac{1}{2.3}+\dfrac{1}{3.4}+...+\dfrac{1}{99.100}\)

Giúp mình nha. Mình cảm ơn trước.

Tìm x

a, \(\left(2-x\right)\times\left(\dfrac{4}{5}-x\right)< 0\)

b, \(\left(x-\dfrac{3}{2}\right)\times\left(2\times x-1\right)>0\)

c, \(\left(x-\dfrac{4}{7}\right)\div\left(x+\dfrac{1}{2}\right)>0\)

d, \(\left(2\times x-5\right)\div\left(x+1\dfrac{3}{4}\right)< 0\)

Giúp mk với

-34/37 . 74/-85

-5/9 : -7/18