\(\dfrac{x}{4}=\dfrac{18}{x+1};x^2+1=72\)
\(\)\(\Rightarrow x\left(x+1\right)=18.4\)
\(\Rightarrow x^2+x=72\)
\(\Rightarrow\left\{{}\begin{matrix}x^2+1=72\\x^2+x=72\end{matrix}\right.\)
\(\Rightarrow x^2+1=x^2+x\)
\(\Rightarrow x=1\)
Câu 1:
a)\(\dfrac{3}{x-1}=\dfrac{4}{y-2}=\dfrac{5}{z-3};x+y+z=18\)
b)\(\dfrac{3}{x-1}=\dfrac{4}{y-2}=\dfrac{5}{z-3};x\cdot y\cdot z=192\)
c)\(2\cdot x=3\cdot y;5\cdot y=3\cdot z;3\cdot x+3\cdot y-7\cdot z=35\)
Câu 2:Tìm 3 số biết tổng các bình phương của chúng bằng 481.Số thứ 2 bằng \(\dfrac{4}{3}\)số thứ nhất và bằng \(\dfrac{3}{4}\)số thứ 3
ĐỀ 2:
1. Tính:
A. \(\left(-\dfrac{2}{3}\right)^2+\left(-\dfrac{7}{8}\right)+\left(-\dfrac{11}{12}\right)\)
B. \(\left(\dfrac{-1}{3}\right)^2:\dfrac{1}{6}-2.\left(\dfrac{-1}{2}\right)^3\)\
C. \(\dfrac{-1}{5}-\left(\dfrac{1}{2}+\dfrac{3}{4}\right)^2:\dfrac{5}{8}\)
D. \(\left|\dfrac{-3}{2}+1,2\right|+1\dfrac{2}{3}:6\)
2. Tìm x, biết:
a. \(\dfrac{2}{3}x-\dfrac{1}{3}x=\dfrac{5}{12}\)
b. \(\left(x-\dfrac{12}{7}\right):1\dfrac{1}{5}=\dfrac{4}{7}\)
c. \(\dfrac{2}{5}+\left|x+1\right|=\dfrac{3}{4}\)
3. Tìm x, y biết:
a. \(\dfrac{x}{18}=\dfrac{y}{15}\)và x - y = -30
b. 7x = 9x và 10x - 8x = 68
c. \(\left(x-\dfrac{1}{2}\right)^{50}+\left(y+\dfrac{1}{3}\right)^{40}=0\)
* Lm nhanh nha
tìm x biết
a) \(\dfrac{x}{27}=\dfrac{-3}{x}\)
b) \(\dfrac{-9}{x}=\dfrac{-x}{\dfrac{4}{49}}\)
c)\(\left|7x-\dfrac{5}{3}\right|+\dfrac{7}{19}=\dfrac{-8}{15}\)
d)\(\left|\dfrac{1}{23}x\right|+\dfrac{18}{90}=\dfrac{18}{19}-1\dfrac{2}{5}\)
Bài 1 Tìm x, y, z
a)\(\dfrac{y+z+1}{x}=\dfrac{x+z+2}{y}=\dfrac{x+y-3}{z}=\dfrac{1}{x+y+z}\)
b)\(\dfrac{2x}{3}=\dfrac{3y}{4}=\dfrac{4z}{5}\)và x+y+z=49
c)\(\dfrac{x-1}{2}=\dfrac{y-2}{3}=\dfrac{z-4}{4}\) và 2x+3y-z=50
d)\(\dfrac{x}{2}=\dfrac{y}{3}=\dfrac{z}{5}\) và xyz=810
Giải cụ thể giúp mình nhé!!!
Tìm x,y,z biết :
a ) \(\dfrac{x}{10}=\dfrac{y}{6}=\dfrac{z}{21}\) bà x + y + z = 25
b ) \(\dfrac{2x}{3}\) = \(\dfrac{3y}{4}=\dfrac{4z}{5}\) và x + y + z = 49
c ) \(\dfrac{x}{2}=\dfrac{y}{3},\) \(\dfrac{y}{4}=\dfrac{z}{5}\) và x + y - z = 10
d ) \(\dfrac{x}{2}=\dfrac{y}{3}=\dfrac{z}{5}\) và x.y.z = 810
ĐỀ 1:
1. Tính:
a. \(\dfrac{7}{23}\left[\left(\dfrac{-8}{6}\right)-\dfrac{45}{18}\right]\)
b. \(\dfrac{1}{5}:\dfrac{1}{10}-\dfrac{1}{3}\left(\dfrac{6}{5}-\dfrac{9}{4}\right)\)
c. \(\dfrac{3}{5}.\left(\dfrac{-8}{3}\right)-\dfrac{3}{5}:\left(-6\right)\)
d. \(\dfrac{1}{2}\left(\dfrac{4}{3}+\dfrac{2}{5}\right)-\dfrac{3}{4}\left(\dfrac{8}{9}+\dfrac{16}{3}\right)\)
e. \(\dfrac{6}{7}:\left(\dfrac{3}{26}-\dfrac{3}{13}\right)+\dfrac{6}{7}\left(\dfrac{1}{10}-\dfrac{8}{5}\right)\)
2. Tìm x, biết:
a. \(1\dfrac{2}{5}x+\dfrac{3}{7}=\dfrac{4}{5}\)
b. |x - 1,5| = 2
c. \(\dfrac{4}{5}-\left|x-\dfrac{1}{6}\right|=\dfrac{2}{3}\)
d. 3x . 2x = 216
e. \(\dfrac{1}{2}\left(x-\dfrac{1}{3}\right)+\dfrac{-1}{2}=\dfrac{3}{4}\)
* Lm nhanh nha
Ths you <3
\(\dfrac{6}{11}x=\dfrac{9}{2}y=\dfrac{18}{5}z\) và -x+z=-196
Tìm x , biết
a) 2 \(|x|\) - 7 = 31 b) 5(x-2) - (x-3) = 1 c)\(\dfrac{x}{5}=\dfrac{y}{4}\) = \(\dfrac{z}{2}\) và x - y + z = 30
Tìm: x, y, z biết
\(\dfrac{y+z+1}{x}=\dfrac{x+z+2}{y}=\dfrac{x+y-3}{z}=\dfrac{1}{x+y+z}\)
