\(a)5^x+5^{x-2}=650\\ \Leftrightarrow\left(5^2+1\right)5^{x-2}=650\\ \Leftrightarrow26.5^{x-2}=650\\ \Leftrightarrow5^{x-2}=25\\ \Leftrightarrow5^{x-2}=5^2\\ \Leftrightarrow x-2=2\\ \Leftrightarrow x=4\)
Tìm x, biết:
a) \(\dfrac{3x+2}{5x+7}=\dfrac{3x-1}{5x+1}\)
b) \(\dfrac{x+1}{2x+1}=\dfrac{0,5x+2}{x+3}\)
Tìm x biết:
a, 5x+2>3x-1
b, \(\dfrac{3}{4}.x-\dfrac{1}{2}>\dfrac{1}{2}.x+\dfrac{3}{4}\)
c, (x-2).(x-3)>0
d, (2x+4)(x-5)<0
a, 4(5x-3)-3(2x+1)=9
b, |x-9|=2x+5
c, \(\dfrac{2}{x-3}+\dfrac{3}{x+3}=\dfrac{3x+5}{x^2-9}\)
Tìm x trong tỉ lệ thức:
\(\dfrac{5x+3}{2\dfrac{1}{7}}=\dfrac{\dfrac{7}{15}}{5x+3}\)
Tìm x ,biết
a,\(\dfrac{1}{3}-\dfrac{2}{5}+3x=\dfrac{3}{4}\)
b,\(\dfrac{3}{2}-1+4x=\dfrac{2}{3}-7x\)
c,\(2.\left(\dfrac{3}{4}-5x\right)=\dfrac{4}{5}-3x\)
d, \(4.\left(\dfrac{1}{2}-x\right)-5.\left(x-\dfrac{3}{10}\right)=\dfrac{7}{4}\)
1, x : y : z = 2 : 3 : 4 và x + y + z = 18
2, \(\dfrac{x}{2}=\dfrac{y}{-3}=\dfrac{z}{4}\) và 4x - 3y - 2z = 81
3, \(\dfrac{x}{3}=\dfrac{y}{2};\) 4y = 3z và x + y +z = 46
4, 5x = 3y; \(\dfrac{y}{z}=\dfrac{3}{2}\) và 2x + 3y -4z =34
Tìm x:
a) \(\left(5x-1\right)^6=729\) b) \(\dfrac{8}{25}=\dfrac{2^x}{5^{x-1}}\) c) \(\left(\dfrac{1}{16}\right)^x=\left(\dfrac{1}{2}\right)^{10}\) d) \(9^x:3^x=3\)
Cho hai đa thức : A(x)= x2-ax+3, B(x)=5x-1. Tìm a biết A(-2)=B(\(\dfrac{1}{10}\))
tìm x,y,z
a)\(\dfrac{1+3y}{12}=\dfrac{1+5y}{5x}=\dfrac{1+7y}{4x}\)
b)\((x-1)=2\left(y-2\right)=3\left(z-3\right)\)và \(2x+3y-z=50\)
c) \(\dfrac{3x-2y}{37}=\dfrac{5y-3z}{15}=\dfrac{2z-5x}{2}\) và \(10-3y-2z=-4\)
d) \(\dfrac{x-1}{2}=\dfrac{y-2}{3}=\dfrac{z-3}{4}\)và \(2x+3y-z=50\)
e) \(ab=\dfrac{1}{2};bc=\dfrac{2}{3};ac=\dfrac{3}{4}\)
f)\(\dfrac{40}{x-30}=\dfrac{20}{y-15}=\dfrac{28}{z-21}\) và \(x.y.z=22400\)
