\(x\times\frac{6}{25}=\frac{15}{-13}\)

x=\(\frac{15}{-13}\div\frac{6}{25}\)

x=\(-\frac{125}{26}\)

các câu còn lại làm tương tự nha!!!

\(1.x.\frac{6}{25}=\frac{15}{-13}\\ x=\frac{15}{-13}:\frac{6}{25}\\ x=-\frac{125}{26}\)

\(2.x:\frac{4}{10}=\frac{13}{-45}+\frac{8}{15}\\ x:\frac{4}{10}=\frac{11}{45}\\ x=\frac{11}{45}.\frac{4}{10}\\ x=\frac{22}{225}\)

\(3.\frac{3}{8}-\frac{1}{6}.x=\frac{1}{4}\\ \frac{1}{6}.x=\frac{3}{8}-\frac{1}{4}\\ \frac{1}{6}.x=\frac{1}{8}\\ x=\frac{1}{8}:\frac{1}{6}\\ x=\frac{3}{4}\)

\(4.\frac{1}{3}+\frac{1}{2}:x=-4\\ \frac{1}{2}:x=-4-\frac{1}{3}=-\frac{13}{3}\\ x=\frac{1}{2}:\left(-\frac{13}{3}\right)=-\frac{3}{26}\)

\(5.x+\frac{7}{12}=\frac{17}{18}-\frac{1}{9}=\frac{5}{6}\\ x=\frac{5}{6}-\frac{7}{12}\\ x=\frac{1}{4}\)

b, S = 2 + 2² + 2³ + ...+2⁹.

2S = 2(2 + 2² + 2³ + ... + 2⁹).

= 2² + 2³ + 2⁴ + ... + 2¹⁰.

2S - S = (2² + 2³ + 2⁴ + ... + 2¹⁰) - (2 + 2² + 2³ + ... + 2⁹).

S = 2¹⁰ - 2.

Vậy S = 2¹⁰ - 2.

~Chúc bn học tốt!!!~

a, \(\dfrac{-1}{5}.\dfrac{6}{7}+\dfrac{3}{7}.\dfrac{3}{5}+\dfrac{2^5.27}{3^3.64}.\)

\(=\dfrac{-1}{5}.\dfrac{3}{7}.2+\dfrac{3}{7}.\dfrac{3}{5}+\dfrac{32.27}{27.64}.\)

\(=\dfrac{3}{7}\left(\dfrac{-1}{5}.2+\dfrac{3}{5}\right)+\dfrac{2.1}{1.2}.\)

\(=\dfrac{3}{7}.\dfrac{1}{5}+1.\)

\(=\dfrac{3}{35}+1.\)

\(=\dfrac{3}{35}+\dfrac{35}{35}.\)

\(=\dfrac{38}{35}.\)

~Chúc bn học tốt!!!~

a.4^7

b.8^5 

 c.cho x mk sẻ tính kết quả nhưng tìm xmk ko tính đâu

b) \(\frac{4^5+4^5+4^5+4^5}{3^5+3^5+3^5}.\frac{6^5+6^5+6^5+6^5+6^5+6^5}{2^5+2^5}=\frac{4^5.\left(1+1+1+1\right)}{3^5.\left(1+1+1\right)}.\frac{6^5.\left(1+1+1+1+1+1\right)}{2^5.\left(1+1\right)}\)

                                                                                                       \(=\frac{4^5.4}{3^5.3}.\frac{6^5.6}{2^5.2}=\frac{4^6}{3^6}.\frac{6^6}{2^6}=\frac{2^{12}.2^6.3^6}{3^6.2^6}=2^{12}\)

   Ta có: \(2^{12}=\left(2^3\right)^4=8^4\)                                                    

Vậy x= 4

a) \(\left(x-\frac{1}{2}\right).\frac{1}{3}+\frac{5}{7}=9\frac{5}{7}\)

\(\left(x-\frac{1}{2}\right).\frac{1}{3}=9\frac{5}{7}-\frac{5}{7}\)

\(x-\frac{1}{2}=9:\frac{1}{3}\)

\(x=27+\frac{1}{2}\)

\(x=\frac{55}{2}\)

b)\(\frac{1}{2}.x+150\%.x=2014\)

\(\left(\frac{1}{2}+150\%\right)x=2014\)

\(2x=2014\)

\(x=2014:2\)

\(x=1007\)

c) \(2-\left|\frac{3}{4}\right|=\frac{7}{2}\)???????

và bài này nữa

tính nhanh

a, \(5\frac{7}{5}\cdot4\frac{2}{7}+5\frac{5}{7}\cdot4\frac{2}{7}\)

b, \(b,\frac{-7}{11}\cdot\frac{4}{19}+\frac{-7}{19}\cdot\frac{7}{11}+2\frac{7}{19}\)

cảm ơn giúp nhiều

\(a,\left(x-\frac{1}{2}\right)\frac{1}{3}+\frac{5}{7}=9\frac{5}{7}\)

\(\Rightarrow\frac{x}{3}-\frac{1}{6}+\frac{5}{7}=\frac{68}{7}\)

\(\Rightarrow\frac{x}{3}-\frac{1}{6}=\frac{63}{7}=9\)

\(\Rightarrow\frac{x}{3}=9+\frac{1}{6}=\frac{55}{6}\)

\(\Rightarrow x=55:2=27,5\)

\(b,\frac{1}{2}.x+150\%.x=2014\)

\(\Rightarrow\frac{x}{2}+\frac{3}{2}.x=2014\)

\(\Rightarrow2x=2014\)

\(\Rightarrow x=2014:2=1007\)

\(c,2-\left|\frac{3}{4}\right|=\frac{7}{12}\)

\(\frac{4}{7}\times x=\frac{1}{5}+\frac{2}{3}\)

\(\frac{4}{7}x=\frac{13}{15}\)

\(\Rightarrow x=\frac{91}{60}\)

các bài còn lại tương tự nha 

mấy cái này dễ mà toán tìm x này là cơ bản!!

67865785685685785785774677567568568

\(\frac{4}{7}\times x-\frac{2}{3}=\frac{1}{5}\)

\(\frac{4}{7}\times x=\frac{2}{3}+\frac{1}{5}\)

\(\frac{4}{7}\times x=\frac{13}{15}\)

\(x=\frac{13}{15}\div\frac{4}{7}\)

\(x=\frac{91}{60}\)

B=\(\left(1-\dfrac{1}{1+2}\right)\). \(\left(1-\dfrac{1}{1+2+3}\right)\).....\(\left(1-\dfrac{1}{1+2+...+100}\right)\)

B=\(\left(1-\dfrac{1}{3}\right)\cdot\left(1-\dfrac{1}{6}\right)\cdot...\cdot\left(1-\dfrac{1}{\left(1+100\right)\cdot100:2}\right)\)

B=\(\dfrac{2}{3}\cdot\dfrac{5}{6}\cdot...\cdot\dfrac{101\cdot100:2-1}{101\cdot100:2}\)

B=\(\dfrac{4}{6}\cdot\dfrac{10}{12}\cdot...\cdot\dfrac{\left(101.100:2-1\right).2}{101.100}\)

B=\(\dfrac{1.4}{2.3}.\dfrac{2.5}{3.4}\cdot...\cdot\dfrac{99.102}{100.101}\)

B=\(\dfrac{1.2.3.4.....99}{3.4.5....100}.\dfrac{4.5.6.....102}{3.4.5.....101}\)

B=\(\dfrac{2}{100}\).\(\dfrac{102}{3}\)

B=\(\dfrac{17}{25}\)