7x + 5 = 5x + 9
=> 7x - 5x = 9 - 5
=> 2x = 4
=> x = 2
7x+ 5 = 5x+ 9
7x-5x = 9 - 5
2x = 4
x = 2
a). 7x-6 = 5x+4 b) 3x-5 = 7x+9
x2−6x+5=0x2−6x+5=0
2x2+7x+9=02x2+7x+9=0
4x2−7x+3=04x2−7x+3=0
2(x+5)=x2+5x
a) 6x-3=8x+9
b) 7x-5=13-5x
c) 2-3x=5x+10
tìm x
x2−6x+5=0x2−6x+5=0
2x2+7x+9=02x2+7x+9=0
4x2−7x+3=04x2−7x+3=0
2(x+5)=x2+5x
Tính
1. ( - 4xy ) . ( 2xy2 - 3x2y)
2. ( -5x ) ( 3x3 + 7x2 - x )
3. ( 3x - 2 ) ( 4x + 5 ) - 6x ( 2x -1 )
4. 2x2 ( x2 - 7x + 9 )
5. ( 3x - 5 ) ( x2 - 5x + 7 )
g) \(|9-7x|=5x-3\)
Vì \(|9-7x|\ge0\)
\(\Rightarrow5x-3\ge0\)
\(\Rightarrow5x\ge3\)
\(\Rightarrow x\ge\frac{3}{5}\)
Ta có: \(|9-7x|=5x-3\)
\(\Leftrightarrow\orbr{\begin{cases}9-7x=5x-3\\7-7x=3-5x\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}-7x-5x=-3-9\\-7x+5x=3-7\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}-12x=-12\\-2x=-4\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=1\left(chon\right)\\x=2\left(chon\right)\end{cases}}\)
\(\Rightarrow x\in\left\{1;2\right\}\)
h) \(8x-|4x+1|=x+2\)
\(\Rightarrow|4x+1|=7x+2\)
Làm tương tự
Giải phương trình
1) 16-8x=0
2) 7x+14=0
3) 5-2x=0
4) 3x-5=7
5) 8-3x=6
6) 8=11x+6
7)-9+2x=0
8) 7x+2=0
9) 5x-6=6+2x
10) 10+2x=3x-7
11) 5x-3=16-8x
12)-7-5x=8+9x
13) 18-5x=7+3x
14) 9-7x=-4x+3
15) 11-11x=21-5x
16) 2(-7+3x)=5-(x+2)
17) 5(8+3x)+2(3x-8)=0
18) 3(2x-1)-3x+1=0
19)-4(x-3)=6x+(x-3)
20)-5-(x+3)=2-5x
a,(x+3)(x^2-3x+9)-(x-3)(x^2+3x+9)
b,(x-5)(x^2+5x+25)-(x+5)(x^2-5x+25)
c,(x-4)(x^2+4x+16)-(x+4)(x^2-4x+18)
d,(x-2)(x^2+7x+49)-(x-7)(x^2-7x+49)
`(3x+1)/3 + (4x+2)/4 + (5x+3)/5 = (7x+1)/7 + (8x+2)/8 + (9x+3)/9`
