Đặt \(a=24-x,b=x-25\)

Khi đó pt ban đầu trở thành :

\(\frac{a^2+ab+b^2}{a^2-ab+b^2}=\frac{19}{49}\)

\(\Leftrightarrow49\left(a^2+ab+b^2\right)=19\left(a^2-ab+b^2\right)\)

\(\Leftrightarrow30a^2+68ab+30b^2=0\)

\(\Leftrightarrow15a^2+34ab+15b^2=0\)

\(\Leftrightarrow\left(3a+5b\right)\left(5a+3b\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}3a=-5b\\5a=-3b\end{cases}}\)

Đến đây bạn thay vào là dễ rồi nhé ! Chúc bạn học tốt !

$A=\dfrac{\left(\dfrac49\right)^2\cdot\left(-\dfrac9{16}\right)\cdot(-1)^{19}}{\left(\dfrac4{25}\right)^2\cdot\left(-\dfrac{25}{144}\right)^2\cdot\left(-\dfrac{49}{144}\right)^2}$

$=\dfrac{\dfrac{16}{81}\cdot\left(-\dfrac9{16}\right)\cdot(-1)}{\dfrac{16}{625}\cdot\dfrac{625}{144^2}\cdot\dfrac{49^2}{144^2}}$

$=\dfrac{\dfrac19}{\dfrac{49^2}{144^4}}$

$=\dfrac19\cdot\dfrac{144^4}{49^2}$

$=\dfrac19\cdot\dfrac{(2^4\cdot3^2)^4}{7^4}$

$=\dfrac19\cdot\dfrac{2^{16}\cdot3^8}{7^4}$

$=\dfrac{2^{16}\cdot3^6}{7^4}$

$=\dfrac{65536\cdot729}{2401}$

$=\dfrac{47775744}{2401}.$

Ta có:

\(\frac{3}{4}.\frac{8}{9}.\frac{15}{16}.\frac{24}{25}.\frac{35}{36}.\frac{48}{49}=\frac{1.3}{2.2}+\frac{2.4}{3.3}+\frac{3.5}{4.4}+\frac{4.6}{5.5}+\frac{5.7}{6.6}+\frac{6.8}{7.7}=\frac{1.2.3.4.5.6}{2.3.4.5.6.7}.\frac{3.4.5.6.7.8}{2.3.4.5.6.7}=\frac{1}{7}.\frac{8}{2}=\frac{4}{7}\)

Lê Tuấn Phong là Kiệt ღ @ ๖ۣۜLý๖ۣۜ tự hỏi tự trả lời 

a, \(\left(2x-1\right)=-8\)

\(2x=-8+1\)

\(2x=-7\)

\(x=-7:2\)

\(x=-3,5\)

a) (2x - 1) = -8

⇒ 2x = -8 + 1

⇒ 2x = -7

b) (3x - 2)\(^2\) = \(\frac{1}{49}\)

Ta có: \(\frac{1}{49}\) = \(\frac{1}{7}\). \(\frac{1}{7}\) hoặc \(\frac{1}{49}\) = \(\frac{-1}{7}\). \(\frac{-1}{7}\)

TH1: 3x - 2 = \(\frac{1}{7}\) TH2: 3x - 2 = \(\frac{-1}{7}\)

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

⇒ 3x = \(\frac{15}{7}\) ⇒ 3x = \(\frac{13}{7}\)

⇒ x = \(\frac{5}{7}\) ⇒ x = \(\frac{13}{21}\)

Vậy: x = \(\frac{5}{7}\) hoặc x = \(\frac{13}{21}\)

a) \(\frac{-6}{35}.\frac{-49}{60}=\frac{\left(-6\right).\left(-49\right)}{35.60}=\frac{\left(-6\right).\left(-7\right).\left(-7\right)}{\left(-5\right).\left(-7\right).\left(-6\right).\left(-10\right)}=\frac{-7}{\left(-5\right).\left(-10\right)}=\frac{-7}{50}\)

b) \(\frac{-16}{25}.\frac{-5}{24}=\frac{\left(-16\right).\left(-5\right)}{25.24}=\frac{\left(-8\right).2.\left(-5\right)}{\left(-5\right).\left(-5\right).\left(-8\right).\left(-3\right)}=\frac{2}{\left(-5\right).\left(-3\right)}=\frac{2}{15}\)

c) \(\frac{15}{-17}.\frac{5}{18}=\frac{15.5}{\left(-17\right).18}=\frac{5.3.5}{\left(-17\right).3.6}=\frac{5.5}{\left(-17\right).6}=\frac{25}{-102}\)

a) \(\frac{-6}{35}\cdot\frac{-49}{60}\)

\(=\frac{\left(-6\right)\cdot\left(-49\right)}{35\cdot60}\)

\(=\frac{294}{2100}=\frac{7}{50}\)

b)\(\frac{-16}{25}\cdot\frac{-5}{24}\)

\(=\frac{\left(-16\right)\cdot\left(-5\right)}{25\cdot24}\)

\(=\frac{80}{600}=\frac{2}{15}\)

c)\(\frac{15}{-17}\cdot\frac{5}{18}\)

\(=\frac{15\cdot5}{\left(-17\right)\cdot18}\)

\(=\frac{75}{-306}=\frac{25}{-102}\)

=\(-\frac{11}{20}\)

$K=\left(\dfrac14-1\right)\left(\dfrac19-1\right)\left(\dfrac1{16}-1\right)\left(\dfrac1{25}-1\right)\left(\dfrac1{36}-1\right)\left(\dfrac1{49}-1\right)\left(\dfrac1{64}-1\right)$

$=\left(-\dfrac34\right)\left(-\dfrac89\right)\left(-\dfrac{15}{16}\right)\left(-\dfrac{24}{25}\right)\left(-\dfrac{35}{36}\right)\left(-\dfrac{48}{49}\right)\left(-\dfrac{63}{64}\right)$

$=(-1)^7\cdot\dfrac34\cdot\dfrac89\cdot\dfrac{15}{16}\cdot\dfrac{24}{25}\cdot\dfrac{35}{36}\cdot\dfrac{48}{49}\cdot\dfrac{63}{64}$

$=-\dfrac34\cdot\dfrac89\cdot\dfrac{15}{16}\cdot\dfrac{24}{25}\cdot\dfrac{35}{36}\cdot\dfrac{48}{49}\cdot\dfrac{63}{64}$

$=-\dfrac{3\cdot8\cdot15\cdot24\cdot35\cdot48\cdot63}{4\cdot9\cdot16\cdot25\cdot36\cdot49\cdot64}$

$=-\dfrac{1\cdot9}{8\cdot7}$

$=-\dfrac9{56}.$

mình biết đáp án là : \(\frac{9}{16}\)thôi,còn cách giải thì mình không chắc chắn nên không viết ra

 \(\frac{3.2.4.3.5.4.6.5.7.6.8.7.9}{4.3.3.4.4.5.5.6.6.7.7.8.8}\)= \(\frac{9}{16}\)