Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
Tìm x:
b) 1/3.x+2/5.(x-1)=0
\(<=> \dfrac{1}{3} .x +\dfrac{2}{5}x - \dfrac{2}{5} =0\)
\(<=> \dfrac{11}{15}x = \dfrac{2}{5}\)
\(<=> x= \dfrac{6}{11}\)
Vậy \( x= \dfrac{6}{11}\)
c) (2x-3).(6-2x)=0
\(<=> \begin{cases}
2x-3=0 \\
6-2x=0
\end{cases}\) \(<=> \begin{cases}
2x=3 \\
-2x=-6
\end{cases}\) \(<=>\begin{cases}
x=\dfrac{3}{2} \\
x=3
\end{cases}\)
Vậy \(x=( \dfrac{3}{2} ; 3)\)
d) -2/3-1/3.(2x-5)= 3/2
\(<=> 2x-5= \dfrac{5}{2}\)
\(<=> 2x= \dfrac{15}{2}\)
\(<=> x= \dfrac{15}{4}\)
Vậy \(x= \dfrac{15}{4}\)
f) 1/3.x-1/2=4 và 1/2 (Hỗn số ý '^')
\(<=> \dfrac{1}{3} x -\dfrac{1}{2} = \dfrac{9}{2}\)
\(<=> \dfrac{1}{3}x =5\)
\(<=> x= 15\)
Vậy \(x= 15\)
\(a,234-\left(x-56\right)=789\)
\(\Leftrightarrow x-56=234-789\)
\(\Leftrightarrow x-56=-555\)
\(\Leftrightarrow x=\left(-555\right)+56=-499\)
Vậy x = -499
b) \(\frac{x+3}{-5}=\frac{x-15}{4}\)
\(\Leftrightarrow4\left(x+3\right)=-5\left(x-15\right)\)
\(\Leftrightarrow4x+12=-5x+75\)
\(\Leftrightarrow4x+12-\left(-5x\right)=75\)
\(\Leftrightarrow4x-\left(-5x\right)+12=75\)
\(\Leftrightarrow4x+5x=63\)
\(\Leftrightarrow9x=63\)
\(\Leftrightarrow x=7\)
Vậy x = 7
c) \(8\left(x-1\right)-7=2\left(x+2\right)+5\)
\(\Leftrightarrow8x-8-7=2x+4+5\)
\(\Leftrightarrow8x-8-7-2x+4=5\)
\(\Leftrightarrow8x-2x-8-7+4=5\)
\(\Leftrightarrow8x-2x=5-4+7+8\)
\(\Leftrightarrow4x=16\)
\(\Leftrightarrow x=4\)
Vậy x = 4
d) Đặt \(D=\frac{2x+3}{x-1}=\frac{2x-2+5}{x-1}=\frac{2\left(x-1\right)+5}{x-1}=2+\frac{5}{x-1}\)
=> \(5⋮x-1\)
=> \(x-1\inƯ\left(5\right)\)
=> \(x-1\in\left\{\pm1;\pm5\right\}\)
=> \(x\in\left\{2;0;6;-4\right\}\)
Tìm x εIN biết
a) 390 - (x-8) = 168:13
b) (x-140) : 7 = 27 - 24
c) x- 6 :2 - ( 48 - 24 ) :2 :6 - 3 = 0
d) x+5.2-(32+16.3:6-15)=0
b) \(\left(x-140\right):7=27-24\)
\(\left(x-140\right):7=3\)
\(x-140=21\)
\(x=161\)
vay \(x=161\)
c) \(x-6:2-\left(48-24\right):2:6-3=0\)
\(x-3-24:2:6-3=0\)
\(x-3-2-3=0\)
\(x-8=0\)
\(x=8\)
vay \(x=8\)
d) \(x+5.2-\left(32+16.3:6-15\right)=0\)
\(x+10-\left(32+8-15\right)=0\)
\(x+10-25=0\)
\(x-15=0\)
\(x=15\)
vay \(x=15\)
a) \(390-\left(x-8\right)=168:13\)
\(390-x+8=\frac{168}{13}\)
\(x+8=390-\frac{168}{13}\)
\(x+8=\frac{5070}{13}-\frac{168}{13}\)
\(x+8=\frac{4902}{13}\)
\(x=\frac{4902}{13}-8\)
\(x=\frac{4798}{13}\)
vay \(x=\frac{4798}{13}\)
Bài 1 :
A ) 3 < x < 5
=> x thuộc { 4 }
Vậy x = 4
Câu b và câu c cứ theo vậy mà làm .
Bài 2 :
| x + 7 | = 0
x = 0 - 7
x = -7
Vậy x = -7
Bài 2 :
a ) l x l < 3
=> l x l thuộc { 0 ; 1 ; 2 }
=> x thuộc { - 2 ; - 1 ; 0 ; 1 ; 2 }
Vậy x thuộc { - 2 ; - 1 ; 0 ; 1 ; 2 }
a) \(x +(x + 1) + (x + 2) + ... + (x +30) = 620\)
\(=\left(x+x+...+x+x\right)+\left(1+2+...+30\right)\)
\(=31x+465=620\)
\(=31x=620-465\)
\(=31x=155\)
\(=x=155\div31\)
\(x=5\)
b) \(2+4+6+8+....+2x = 210\)
\(\Rightarrow2.1+2.2+2.3+2.4+...+2.x\)
\(\Rightarrow2.\left(2+4+6+8+...+x\right)=210\)
\(\Rightarrow2+4+6+8+x=210\div2\)
\(\Rightarrow2+4+6+8+...+x=105\)
\(\Rightarrow x=14\)
Bài 1 :
a) x={2,4}
b) x-1={-3,-2,-1,0,1,2,3,4}
=> x={-2,-1,0,1,2,3,4,5}
c) x+2={-7,-6,-5,-4}
=> x={-9,-8,-7,-6}
Bài 2 :
(x-3)(x+2)=0
=> x-3=0 => x=3
=> x+2=0 => x=-2
Vậy x=-2 hoặc x=3
BÀI 1
A) 3<X<5
=>X=4
B) -4<X+2<5
=>X-1\(\in\left(-3;-2;-1;0;1;2;3;4\right)\)
=> X-1=-3 => X-1=-2 =>X-1=-1 =>X-1=0 => X-1=1
X=-2 X=-1 X= 0 X=1 X=2
=>X-1=2 => X-1=3 =>X-1=4
X=3 X=4 X=5
C) -8<X+2<-3
=> X+2\(\in\left(-7;-6;-5;-4\right)\)
=> X+2=-7 =>X+2=-6 =>X+2=-5 =>X+2=-4
X=-9 X=-8 X=-7 X=-6
BÀI 2
\(\left(X-3\right).\left(X+2\right)=0\)
\(\Rightarrow X-3=X+2=O\)
\(TH1:X-3=0\)
X=3
TH2: X+2=0
X=-2
VẬY X=3 HOẶC X=-2
a ) + ) Xét x \(\ge\) 3 => |x - 3| = x - 3
=> |x - 3| + x - 3 = x - 3 + x - 3 = 0
<=> 2x - 6 = 0
<=> 2x = 6
=> x = 3
+ ) Xét x < 3 => |x - 3| = 3 - x
=> |x - 3| + x - 3 = 3 - x + x - 3 = 0
<=> 0 = 0 ( loại )
Vậy x = 3
ý khác tương tự