\(\dfrac{y+3}{y-6}=\dfrac{y-4}{y+1}\\ \Rightarrow\left(y+3\right)\left(y+1\right)=\left(y-4\right)\left(y-6\right)\\ \Rightarrow y^2+4y+3=y^2-10y+24\\ \Rightarrow4y+3=-10y+24\\ \Rightarrow14y=21\\ \Rightarrow y=\dfrac{3}{2}\)
Tìm y biết :
a) \(-\dfrac{3}{5}.y=\dfrac{21}{10}\)
b) \(y:\dfrac{3}{8}=-1\dfrac{31}{33}\)
c) \(1\dfrac{2}{5}.y+\dfrac{3}{7}=-\dfrac{4}{5}\)
d) \(-\dfrac{11}{12}.y+0,25=\dfrac{5}{6}\)
Tìm y, biết:
a) \(-\dfrac{3}{5}\times y=\dfrac{21}{10}\)
b) \(y\div\dfrac{3}{8}=-1\dfrac{31}{33}\)
c) \(1\dfrac{2}{5}\times y+\dfrac{3}{7}=-\dfrac{4}{5}\)
d) \(-\dfrac{11}{12}\times y+0,25=\dfrac{5}{6}\)
a,Tìm x,y,z biết: \(\dfrac{y+z+1}{x}\)=\(\dfrac{x+z+2}{y}\)=\(\dfrac{x+y-3}{z}\)=\(\dfrac{1}{x+y+z}\)
b,Cho \(\dfrac{a}{b}\)=\(\dfrac{b}{c}\)=\(\dfrac{c}{d}\). Chứng minh rằng: (\(\dfrac{a+b+c}{b+c+d}\))3=\(\dfrac{a}{d}\)
c,Cho \(\dfrac{a}{b}\)=\(\dfrac{c}{d}\). Chứng minh rằng: \(\dfrac{5a+3b}{5c+3d}\)=\(\dfrac{5a-3b}{5c-3d}\)
d,Cho \(\dfrac{3x-2y}{4}\)=\(\dfrac{2z-4x}{3}\)=\(\dfrac{4y-3z}{2}\).Chứng minh rằng: \(\dfrac{x}{2}\)=\(\dfrac{y}{3}\)=\(\dfrac{z}{4}\)
tìm x, y, z khi
1) \(\dfrac{x}{7}=\dfrac{y}{3}\) và x-24=y
2) \(\dfrac{x}{5}=\dfrac{y}{7}=\dfrac{z}{2}\) và y-x=48
3) \(\dfrac{x-1}{2005}=\dfrac{3-y}{2006}\) và x-y=4009
4) \(\dfrac{x}{2}=\dfrac{y}{3};\dfrac{y}{4}=\dfrac{z}{5}\) và x-y-z=28
5) \(\dfrac{x}{3}=\dfrac{y}{5}=\dfrac{z}{7}\) và 2x+3y-z=-14
6) 3x=y; 5y=4z và 6x+7y+8z=456
Bài 1:
a) \(\dfrac{1}{2}x+\dfrac{5}{6}=\dfrac{-3}{4}\)
Bài 2:
a) x + y = 30 và \(\dfrac{x}{2}=\dfrac{y}{3}\)
b) x - y = 15 và \(\dfrac{x}{3}=\dfrac{y}{7}\)
Tìm x, y, z biết rằng:
a) \(\dfrac{x}{y+z+1}=\dfrac{y}{z+x+1}=\dfrac{z}{x+y-2}=x+y+z\)
b)\(\dfrac{y+z+1}{x}=\dfrac{z+x+2}{y}=\dfrac{x+y-3}{z}+=\dfrac{1}{x+y+z}\)
TÌM X,Y,Z BIẾT:
A.\(\dfrac{1}{x}+\dfrac{1}{y}+\dfrac{1}{z}\) = 3 và 2x = -3y = 4z
B.\(\dfrac{x-1}{2}=\dfrac{y-2}{3}=\dfrac{z-3}{4}\)và x- 2y +3z = 14
3,Tìm 3 số tự nhiên x,y,z biết :
\(\dfrac{y+x+1}{x}=\dfrac{z+x+2}{y}=\dfrac{x+y-3}{z}=\dfrac{1}{x+y+z}\)
Tìm x ; y ; z biết :
a. \(\dfrac{x}{10}=\dfrac{y}{6}=\dfrac{z}{27}\) và 5x+y-27 = 28
b. x : y:z = 5:4:2 và x3 - y3 + z3=69
c. \(\dfrac{x}{3}=\dfrac{z}{8}\) và -6y=72 ; 2x-9y=2
