x = -19 x 3 : (-57) = 1

y = -19 x (-9) : (-57) = 3

z = -57 x (-8) : (-19) = 24

Tk mình nha mọi người!!!!

Ta có:

    \(\frac{x}{3}=\frac{y}{-9}=\frac{8}{-z}=\frac{-19}{-57}\) 

\(\Rightarrow\frac{x}{3}=\frac{-y}{9}=\frac{-8}{z}=\frac{19}{57}\)

\(\Rightarrow\frac{x}{3}=\frac{19}{57}\)

\(\Rightarrow x\times57=19\times3=57\)

\(\Rightarrow x=57\div57=1\)

\(\Rightarrow\frac{1}{3}=\frac{-y}{9}\)

\(\Rightarrow-y\times3=1\times9=9\)

\(\Rightarrow-y=9\div3=3\)

\(\Rightarrow y=-3\)

\(\Rightarrow\frac{-3}{-9}=\frac{3}{9}=\frac{-8}{z}\)

\(\Rightarrow3\times z=-8\times9=-72\)

\(\Rightarrow z=-72\div3=-24\)

Vậy các giá trị x,y,z thỏa mãn đề bài là:

x=1;y=-3,z=-24

x=1,y=-3,z=-24 vì -19/-57=1/3 

x = 9

\(\dfrac{57}{x+3}-\dfrac{39}{x}=\dfrac{5}{12}\)

\(\Leftrightarrow57.12x-39.12\left(x+3\right)=5x\left(x+3\right)\)

\(\Leftrightarrow684x-468x-1404=5x^2+15x\)

\(\Leftrightarrow216x-1404-5x^2-15x=0\)

\(\Leftrightarrow201x-1404-5x^2=0\)

\(\Leftrightarrow5x^2-201x+1404=0\)

\(\Leftrightarrow5x^2-45x-156x+1404=0\)

\(\Leftrightarrow5x\left(x-9\right)-156\left(x-9\right)=0\)

\(\Leftrightarrow\left(5x-156\right)\left(x-9\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}5x-156=0\\x-9=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{156}{5}\\x=9\end{matrix}\right.\)

Chưa học delta thì làm theo cách này nhé :>

Ta có: \(\dfrac{57}{x+3}-\dfrac{39}{x}=\dfrac{5}{12}\)

\(\Leftrightarrow\dfrac{18x-117}{x\left(x+3\right)}=\dfrac{5}{12}\)

\(\Leftrightarrow5x^2+15x=216x-1404\)

\(\Leftrightarrow5x^2-201x+1404=0\)

\(\text{Δ}=201^2-4\cdot5\cdot1404=12321\)

Vì Δ>0 nên phương trình có hai nghiệm phân biệt là:

\(\left\{{}\begin{matrix}x_1=\dfrac{201-111}{10}=9\\x_2=\dfrac{201+111}{10}=\dfrac{156}{5}\end{matrix}\right.\)

mn giúp em mình với

\(A=\frac{4^5.9^4-2.6^9}{2^{10}.3^8-6^8.20}\)

\(A=\frac{\left(2^2\right)^5.\left(3^2\right)^4-2.\left(2.3\right)^9}{2^{10}.3^8-\left(2.3\right)^8.2^2.5}\)

\(A=\frac{2^{10}.3^8-2^{10}.3^9}{2^{10}.3^8-2^{10}.3^8.5}\)

\(A=\frac{2^{10}.\left(3^8-3^9\right)}{2^{10}.3^8.\left(1-5\right)}=\frac{3^8-3^9}{3^8.\left(-4\right)}=\frac{3^8.\left(1-3\right)}{3^8.\left(-4\right)}=\frac{-2}{-4}=\frac{1}{2}\)

Vậy A = \(\frac{1}{2}\)

\(B=\frac{2^{19}.27^3+15.4^9.9^4}{6^9.2^{10}+12^{10}}\)

\(B=\frac{2^{19}.\left(3^3\right)^3+3.5.\left(2^2\right)^9.\left(3^2\right)^4}{\left(2.3\right)^9.2^{10}+\left(2^2.3\right)^{10}}\)

\(B=\frac{2^{19}.3^9+3.5.2^{18}.3^8}{2^9.3^9.2^{10}+2^{20}.3^{10}}\)

\(B=\frac{2^{19}.3^9+3^9.2^{18}.5}{2^{19}.3^9+2^{20}.3^{10}}\)

\(B=\frac{2^{18}.3^9.\left(2+5\right)}{2^{19}.3^9\left(1+2.3\right)}=\frac{7}{2.7}=\frac{1}{2}\)

Vậy B = \(\frac{1}{2}\)

 mik ko chép lại đề, mik làm luôn: 

a)  x - \(\frac{31}{36}=\frac{-13}{38}\)

x = \(\frac{-13}{18}+\frac{31}{36}\)

\(x=\frac{5}{36}\)

b)\(2-x-\frac{3}{7}=\frac{9}{-21}\)

\(\frac{11}{7}-x=\frac{3}{7}\)

x = \(\frac{11}{7}-\frac{3}{7}\)

x = 8/7

c) x + 3/11 = 23/44

x = 23/44 - 3/11

x = 1/4

d) \(\frac{1}{12}-x=\frac{-11}{9}\)

x = \(\frac{1}{12}+\frac{11}{9}\)

x = 47/36

e) \(x-\frac{2}{3}=\frac{-17}{3}\)

x= -17/3 + 2/3

x = -5 

f) \(x-\frac{1}{2}=\frac{11}{4}.\frac{3}{11}\)

x - 1/2 = 3/4

x = 3/4 + 1/2 

x = 5/4

g) \(2x+\frac{3}{8}=\frac{-21}{32}.\frac{4}{7}\)

2x + 3/8 = -3 / 8

2x = -3/8 - 3/8 

2x = -9/8

x = -9/8.1/2 

x = -9/16

h) x - \(\frac{x}{3}=\frac{3}{57}.\frac{19}{12}\)

x  - \(\frac{x}{3}=\frac{1}{12}\)

x = \(\frac{1}{12}+\frac{x}{3}\)

x = \(\frac{1+4x}{12}\)

=> 12x = 1+4x

12x - 4x = 1

8x = 1

x = 1/8 

Trả lời nhanh gọn lẹ nhé, mình k cho :)

a) \(x-\frac{5}{12}-\frac{4}{9}=\frac{-13}{18}\)

  \(x-\frac{5}{12}=\frac{-13}{18}+\frac{4}{9}\)

  \(x-\frac{5}{12}=\frac{-13}{18}+\frac{8}{18}\)

  \(x-\frac{5}{12}=\frac{-5}{18}\)

 \(x=\frac{-5}{18}+\frac{5}{12}\)

....

Mình biết cách làm nhưng mình lười không buồn tính. Tìm người khác giúp bạn nhé!

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