\(\dfrac{4x}{2x+9}=8\)
=>16x+72=4x
=>12x=-72
=>x=-6
\(\dfrac{9^{x+9}}{3^{5y}}=243\)
\(\Leftrightarrow\dfrac{9^{-6+9}}{3^{5y}}=243\)
\(\Leftrightarrow3^{5y}=\dfrac{9^3}{243}=3\)
=>5y=1
hay y=1/5
=>xy=-6/5
Bài 1: tìm các số x,y,z
a,\(\dfrac{x}{4}=\dfrac{7}{3}=\dfrac{z}{9}\) và x-3y+4z=62
b,\(\dfrac{x}{y}=\dfrac{9}{7}\);\(\dfrac{y}{z}=\dfrac{7}{3}\)và x-y+z=-15
c,\(\dfrac{x}{y}=\dfrac{7}{20}\);\(\dfrac{y}{x}=\dfrac{7}{3}\)và 2x+5y-2z=100
Bài 1: tìm các số x,y,z
a,\(\dfrac{x}{4}\)=\(\dfrac{y}{3}\)=\(\dfrac{z}{9}\)và x-3y+4z=62
b,\(\dfrac{x}{y}\)=\(\dfrac{9}{7}\);\(\dfrac{y}{z}\)=\(\dfrac{7}{3}\)và x-y+z=-15
c,\(\dfrac{x}{y}\)=\(\dfrac{7}{20}\);\(\dfrac{y}{z}=\dfrac{7}{3}\) và 2x+5y-2z=100
bài 2 tìm các số x,y,z
a,5x=8y=20z và x-y-z=3
b,\(\dfrac{6}{11}\)x=\(\dfrac{9}{2}y\)=\(\dfrac{18}{5}z\) và -x+y+z=-120
bài 3:tìm x,y,z biết
a,\(\dfrac{x}{12}\)=\(\dfrac{y}{9}=\dfrac{z}{5}\)và xyz=20
b,\(\dfrac{x}{5}=\dfrac{y}{7}=\dfrac{z}{3}\)và x2 + y2 -z2 =585
Tìm x biết:
\(\dfrac{9}{8}+\dfrac{3}{8}:x=0,25\)
(\(\dfrac{2x}{5}-1\)):(-5)\(=\dfrac{1}{7}\)
Tìm x \(\in\) Z biết;
a) \(\dfrac{x}{15}=\dfrac{4}{y}=\dfrac{-2}{5}\)
b) \(\dfrac{x-3}{4}=\dfrac{15}{20}\)
c) \(\dfrac{-5}{9}+\dfrac{-8}{15}+\dfrac{22}{-9}+\dfrac{-7}{15}< x\le\dfrac{-1}{3}+\dfrac{-1}{4}+\dfrac{-5}{12}\)
Tìm x biết :
1/\(\dfrac{4}{3}\) + x = \(\dfrac{2}{15}\) 2/\(\dfrac{1}{3}+\dfrac{1}{2}:\) x = -0,25 3/(\(\dfrac{2x}{5}+2\) ):(-4) = -1\(\dfrac{1}{2}\) 4/ x.( x + 1) = 0 5/3\(\dfrac{1}{2}-\dfrac{1}{2}x\) = \(\dfrac{2}{3}\)
6/1\(\dfrac{1}{2}+x=\dfrac{3}{2}-7\) 7/\(2x-16=40+x\) 8/\(x:\dfrac{5}{3}+\dfrac{1}{3}=\dfrac{-2}{5}\) 9/\(\dfrac{x}{4}=\dfrac{9}{x}\)
Tìm x \(\in\) N
x : (9\(\dfrac{1}{2}\) - \(\dfrac{3}{2}\)) = \(\dfrac{0,4+\dfrac{2}{9}-\dfrac{2}{11}}{1,6+\dfrac{8}{9}-\dfrac{8}{11}}\)
tìm x,y,z:
\(\dfrac{x-3}{8}\)=\(\dfrac{y-1}{3}\) và 4x-5y=10
bài 1 tìm x,y,z
a, \(\dfrac{x}{10}\)=\(\dfrac{y}{15}\),x=\(\dfrac{7}{2}\) và x +2y-3z=20
b,2x=3y,49=57 và 4x-3y+5z=7
c, \(\dfrac{2x}{3}\)=\(\dfrac{3y}{4}\)=\(\dfrac{47}{5}\) và x+y+z=49
bài 2 tìm x trong tỉ lệ thức sau
a, \(\dfrac{x-3}{x+5}=\dfrac{5}{7}\)
b,\(\dfrac{7}{x-1}\) =\(\dfrac{x+1}{9}\)
c,\(\dfrac{x+4}{20}=\dfrac{2}{x+4}\)
d,\(\dfrac{x-1}{x+2}=\dfrac{x-2}{x+3}\)
Tìm số x , biết
a) \(\dfrac{2}{3}x-\dfrac{3}{2}x=\dfrac{5}{12}\)
b) \(\dfrac{2}{5}+\dfrac{3}{5}.\left(3x-3,7\right)=-\dfrac{53}{10}\)
c) \(\dfrac{7}{9}:\left(2+\dfrac{3}{4}x\right)+\dfrac{5}{9}=\dfrac{23}{27}\)
d) \(\dfrac{-2}{3}.x+\dfrac{1}{5}=\dfrac{3}{10}\)
e) \(\left|x\right|-\dfrac{3}{4}=\dfrac{5}{3}\)
f) \(\left|2x-\dfrac{1}{3}\right|+\dfrac{5}{6}=1\)
