12 - 1/2 + 2x= 8 - 3x
12 - 1/2 - 8= -3x - 2x
-5x= 3,5
=> x= - 0,7
Vậy x= 0,7
Vậy x= - 0,7 nha, mk đánh lộn xin lỗi, hihi
1. tìm x
a, 2x - \(\dfrac{1}{2}\) : \(\dfrac{3}{4}\) = \(\dfrac{12}{9}\)
b, x\(^2\) - 2 = 0
2. Cho
A = \(\dfrac{1,11+0,19-13.2}{2,06+0,54}\) - \(\left(\dfrac{1}{2}+\dfrac{1}{4}\right)\) : 2
B = \(\left(5\dfrac{7}{8}-2\dfrac{1}{4}-0,5\right)\) : \(2\dfrac{23}{26}\)
a, Rút gọn A, B
b, Tìm x ϵ Z để A < x < B
Thu gọn các đơn thức đồng dạng trong đa thức sau:
a) \(A=x^5-\dfrac{1}{2}x+7x^3-2x+\dfrac{1}{5}x^3+3x^4-x^5+\dfrac{2}{5}x^4+15\)
b) \(B=3x^2-10+\dfrac{2}{5}x^3+7x-x^2+8+7x^2\)
c) \(C=\dfrac{1}{7}x-2x^4+5x+6\)
Tìm x :
(2,5-3x):\(1\dfrac{2}{3}\)=\(\left(\dfrac{8}{5}+2x\right):\left(-\dfrac{8}{17}\right)\)
Tìm các cặp số ( x : y ) nguyên sao cho :
a, x - y + 2 xy = 3
b,\(3x^2-3xy-5x-y=-20\)
c,\(\dfrac{x}{8}-\dfrac{1}{y}=\dfrac{1}{4}\)
d,\(2x+\dfrac{1}{7}=\dfrac{1}{y}\)
Tìm x biết :
1) \(\dfrac{-7}{x+1}=\dfrac{-x-1}{\dfrac{4}{7}}\)
2) \(\dfrac{x-3}{x+5}=\dfrac{5}{7}\)
3) \(\dfrac{x+1}{2x+1}=\dfrac{0,5x+2}{x+3}\)
4) \(\dfrac{3x+2}{5x+7}=\dfrac{3x-1}{5x+1}\)
1)Tính giá trị biểu thức:
\(\dfrac{\left(13\dfrac{1}{4}-2\dfrac{5}{27}-10\dfrac{5}{6}\right).230\dfrac{1}{25}+46\dfrac{3}{4}}{\left(1\dfrac{3}{7}+\dfrac{10}{3}\right):\left(12\dfrac{1}{3}-14\dfrac{2}{7}\right)}\)
2)Tìm x biết:
a) \(42+\dfrac{3}{7}.\left|3x-1\right|=12\)
b) \(\left|2x-1\right|=\left|x+2\right|\)
c) \(2.3^x.3^2=18\) với \(x\in N\)
1)Tìm x, biết:
a)\(\dfrac{x-1}{3}=\dfrac{x+1}{5}\)
b)\(\dfrac{2x+1}{3x-2}=\dfrac{5x+1}{9x+1}\)
2)Tìm x,y,z biết:
a)\(\dfrac{x}{2}=\dfrac{y}{3}=\dfrac{z+1}{4}\) và 2x+3y-z=11
b)\(\dfrac{2x+1}{5}=\dfrac{3y-2}{7}=\dfrac{2x+3y-1}{6x}\)
Giúp mình với mình đang cần gấp!!!THANK NHÌU 
\(^{\dfrac{-7}{1+2x}}=\dfrac{5}{2-3x}\)
tìm x biết
\(\dfrac{2x+3}{0.5}=\dfrac{2x^2}{3x}\)
