BT1:  Cho C=\(\frac{1}{3}\)+\(\frac{1}{5}\)+\(\frac{1}{9}\)+\(\frac{1}{17}\)+\(\frac{1}{33}\)+\(\frac{1}{65}\)

Hãy so sánh C với 1

D=\(\frac{1}{5^2}\)-\(\frac{2}{5^3}\)+\(\frac{3}{5^4}\)-\(\frac{4}{5^5}\)+......+\(\frac{99}{5^{100}}\)-\(\frac{100}{5^{101}}\)

Hãy so sánh D với \(\frac{1}{16}\)

Câu 1 : Tính

a) \(\frac{2}{3}\)+\(\frac{1}{3}\)x ( \(\frac{-4}{9}\)+\(\frac{5}{6}\)) : \(\frac{7}{12}\)

b) S = \(\frac{1}{2}\)x \(\frac{1}{3}\)+\(\frac{1}{3}\)x\(\frac{1}{4}\)+\(\frac{1}{4}\)x\(\frac{1}{5}\)+\(\frac{1}{5}\)x\(\frac{1}{6}\)+\(\frac{1}{6}\)x\(\frac{1}{7}\)+\(\frac{1}{7}\)x\(\frac{1}{8}\)+\(\frac{1}{8}\)x\(\frac{1}{9}\)

c) A = \(\frac{5}{5.7}\)+\(\frac{5}{7.9}\)+...+\(\frac{5}{59.61}\)

d) M = \(\frac{3}{4}\)x\(\frac{8}{9}\)x\(\frac{15}{16}\)x\(\frac{24}{25}\)x...x\(\frac{99}{100}\)

e) N = \(\frac{1}{2}\)x\(\frac{-2}{3}\)x\(\frac{3}{4}\)x\(\frac{-4}{5}\)x\(\frac{5}{6}\)x\(\frac{-6}{7}\)x...x\(\frac{-98}{99}\)x\(\frac{99}{100}\)

[ Các bạn trả lời cách tính nhanh mà đúng nhá :)) ]

[ Cảm ơn các bạn nhiều <3 ]

bài 2 tìm x

a,\(\frac{-2}{3}.x+\frac{1}{5}=\frac{3}{10}\)

b,\(\left|x\right|-\frac{3}{4}=\frac{5}{3}\)

c,\(\frac{2}{3}.x-\frac{1}{2}=\frac{1}{10}\)

d,\(\frac{3}{5}+\frac{4}{9}:x=\frac{2}{3}\)

e,\(\left|x+75\%\right|=2\frac{1}{5}\)

i,\(\left(x+\frac{1}{2}\right).\left(\frac{2}{3}-2.x\right)=0\)

k,\(\frac{4}{7}.x-\frac{2}{3}=\frac{1}{5}\)

l,\(\frac{2}{3}.x-\frac{3}{2}.x=\frac{5}{12}\)

m,\(\left|2.x-\frac{1}{3}\right|+\frac{5}{6}=1\)

n,\(\frac{1}{3}-\frac{7}{8}.x=\frac{1}{3}\)

11,\(\frac{x+2}{5}=\frac{7}{12}-1\frac{1}{4}\)

12,\(\left(2\frac{4}{5}.x-50\right):\frac{2}{3}=51\)

13,\(\frac{2}{5}+\frac{3}{5}.\left(3.x-3,7\right)=-\frac{53}{10}\)

14,\(\frac{7}{9}:\left(2+\frac{3}{4}.x\right)+\frac{5}{9}=\frac{23}{27}\)

Tìm x

a) 2x-\(\frac{2}{3}\)-7x = \(\frac{3}{2}\)-1

b) \(\frac{3}{2}\)x-\(\frac{2}{5}\)=\(\frac{1}{3}\)x - \(\frac{1}{4}\)

c)\(\frac{2}{3}\) - \(\frac{5}{3}\)x = \(\frac{7}{10}\)x +\(\frac{5}{6}\)

d) 2x -\(\frac{1}{4}\)= \(\frac{5}{6}\) - \(\frac{1}{2}\)x

e) 3x -\(\frac{5}{3}\)= x-\(\frac{1}{4}\)

Giúp mk với mn người ơiiii

1.a.So sánh : \(\frac{97}{100}\)và \(\frac{101}{103}\)

b.Chứng tỏ phân số: \(\frac{3n-7}{2n-5}\left(n\inℤ\right)\)là phân số tối giản

2.Tìm x biết:

a.\(\frac{1}{3}x-\frac{1}{4}=\frac{3}{5}x+1\)

b.\(\frac{2}{3}\left(\frac{1}{2}x-\frac{1}{4}\right)=\frac{4}{5}x+\frac{1}{2}\)

3.Chứng tỏ :

\(A=\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...............+\frac{1}{12}>2\)

Bài 1:tính nhanh

a. 6\(\frac{4}{5}\)-\(\left(1\frac{2}{3}+3\frac{4}{5}\right)\)

b. \(7\frac{5}{9}-\left(2\frac{3}{4}+3\frac{5}{9}\right)\)

c. \(\frac{-3}{5}.\frac{5}{7}+\frac{-3}{5}.\frac{3}{7}+\frac{-3}{5}.\frac{6}{7}\)

d. \(\frac{1}{3}.\frac{4}{5}+\frac{1}{3}.\frac{6}{5}-\frac{4}{3}\)

Bài 2: tìm x

a. \(\frac{2}{3}+\frac{1}{3}:x=\frac{3}{5}\)

b. \(x+30\%x=-1,3\)

c. \(3\frac{1}{3}x+16\frac{3}{4}=-13,25\)

d. \(\left(2\frac{4}{5}x-50\right):\frac{2}{3}=51\)

e. |2x-1|=\(\left(-4\right)^2\)

gấp nha các bạn !!!!!!!!

bài 1

a,\(\frac{x}{5}\)=\(\frac{2}{3}\)

b,\(\frac{x}{3}\)-\(\frac{1}{2}\)=\(\frac{1}{5}\)

c,\(\frac{x}{5}\)+\(\frac{1}{2}\)=\(\frac{6}{10}\)

d,\(\frac{x+3}{15}\)=\(\frac{1}{3}\)

e,\(\frac{x-12}{4}\)=\(\frac{1}{2}\)

h,\(\frac{4}{5}\)+x=\(\frac{2}{3}\)

i,\(\frac{3}{4}\)-x=\(\frac{1}{3}\)

k,\(\frac{-5}{6}\)-x=\(\frac{2}{3}\)

l,x-\(\frac{5}{9}\)=\(\frac{-2}{3}\)

m,\(\frac{1}{2}\)x+\(\frac{1}{2}\)=\(\frac{5}{2}\)

n,\(\frac{-2}{3}\)-\(\frac{1}{3}\)(2x-5)=\(\frac{3}{2}\)

p,(3x-1)(\(-\frac{1}{2}\)x+5)=0

q,\(3\frac{1}{3}\)+\(\frac{5}{6}\)x=\(3\frac{1}{2}\)

s,\(\frac{1}{2}\)-\(\frac{2}{3}\)x=\(\frac{7}{12}\)

t,\(\frac{3}{4}\)x+\(\frac{1}{5}\)=\(\frac{1}{6}\)

u,\(\frac{3}{8}\)-\(\frac{1}{6}\)x=\(\frac{1}{4}\)

mn ơi'-' xin hãy giúp mk với ạ>^<,mk cần rất gấp,mai nộp r ạ,mong mn giúp mk với ạ:(( huhuhu r mk tik cho:<<