a) x−12+4x=25+2x−1x−12+4x=25+2x−1

⇔5x – 12 = 2x + 24

⇔5x – 2x = 24 + 12

⇔3x = 36

⇔x = 12

Vậy phương trình có nghiệm x = 12.

b) x+2x+3x−19=3x+5x+2x+3x−19=3x+5

⇔6x – 19 = 5x +3x

⇔3x= 24

⇔x= 8

Vậy phương trình có nghiệm x = 8.

a) x−12+4x=25+2x−1x−12+4x=25+2x−1

⇔5x – 12 = 2x + 24

⇔5x – 2x = 24 + 12

⇔3x = 36

⇔x = 12

Vậy x=12 là nghiệm của phương trình

b) x+2x+3x−19=3x+5x+2x+3x−19=3x+5

⇔6x – 19 = 5x +3x

⇔3x= 24

⇔x= 8

Vậy x=8 là nghiệm của phương trình

a)x−12+4x=25+2x−1x−12+4x=25+2x−1

⇔5x – 12 = 2x + 24

⇔5x – 2x = 24 + 12

⇔3x = 36

⇔x = 12

Vậy phương trình có nghiệm x = 12.

b) x+2x+3x−19=3x+5x+2x+3x−19=3x+5

⇔6x – 19 = 5x +3x

⇔3x= 24

⇔x= 8

Vậy phương trình có nghiệm x = 8.

1.

$\sqrt{3x^2}-\sqrt{12}=0$

$\Leftrightarrow \sqrt{3x^2}=\sqrt{12}$

$\Leftrightarrow 3x^2=12$

$\Leftrightarrow x^2=4$

$\Leftrightarrow (x-2)(x+2)=0\Leftrightarrow x=\pm 2$

2. 

$\sqrt{(x-3)^2}=9$

$\Leftrightarrow |x-3|=9$

$\Leftrightarrow x-3=9$ hoặc $x-3=-9$

$\Leftrightarrow x=12$ hoặc $x=-6$

Lời giải:

b.

$3x+1=5x+2$

$\Leftrightarrow 1-2=5x-3x$

$\Leftrightarrow -1=2x\Leftrightarrow x=\frac{-1}{2}$

d.

$6x-4=7-5x$

$\Leftrightarrow 6x+5x=4+7$

$\Leftrightarrow 11x=11\Leftrightarrow x=1$

f.

$x-12+4x=25+2x-1$
$\Leftrightarrow 5x-12=24+2x$

$\Leftrightarrow 5x-2x=24+12$

$\Leftrightarrow 3x=36$

$\Leftrightarrow x=12$

`b,2(x+1)=5x-7`

`=>2x+2=5x-7`

`=>3x=9`

`=>x=3`

`d,(10x+3)/12=1+(6+8x)/9`

`<=>(10x+3)/12=(8x+15)/9`

`<=>30x+9=32x+60`

`<=>2x=-51`

`<=>x=-51/2`

a) \(PT\Leftrightarrow3x-2x=2-3\Leftrightarrow x=-1\)

Vậy: \(S=\left\{-1\right\}\)

b) \(PT\Leftrightarrow-2x+3x=-7+22\Leftrightarrow x=15\)

Vậy: \(S=\left\{15\right\}\)

c) \(PT\Leftrightarrow8x-5x=3+12\Leftrightarrow3x=15\Leftrightarrow x=5\)

Vậy: \(S=\left\{5\right\}\)

d) \(PT\Leftrightarrow x+4x-2x=12+25-1\Leftrightarrow3x=36\Leftrightarrow x=12\)

Vậy: \(S=\left\{12\right\}\)

e) \(PT\Leftrightarrow x+2x+3x-3x=19+5\Leftrightarrow3x=24\Leftrightarrow x=8\)

Vậy: \(S=\left\{8\right\}\)

a)3x-2=2x-3

=>x=-1

b)7-2x=22-3x

=>x=15

c)8x-3=5x+12

=>3x=15

=>x=5

d)x-12+4x=25+2x-1

=>3x=12

=>x=4

e)x+2x+3x-19=3x+5

=>3x=24

=>x=8

\(a,8x-3=5x+12\\ \Leftrightarrow8x-5x=12+3\\ \Leftrightarrow3x=15\\ \Leftrightarrow x=\dfrac{15}{3}=5\)

\(b,x-12+4x=25+2x-1\\ \Leftrightarrow x+4x-2x=25-1+12\\ \Leftrightarrow3x=36\\ \Leftrightarrow x=\dfrac{36}{3}=12\)

\(c,7-\left(2x+4\right)=-\left(x+4\right)\\ \Leftrightarrow7-2x-4=-x-4\\ \Leftrightarrow-2x+x=-4+4-7\\ \Leftrightarrow-x=-7\\ \Leftrightarrow x=7\)

\(d,3-4x\left(45-2x\right)=8x^2+x-300\\ \Leftrightarrow3-100x+8x^2=8x^2+x-300\\ \Leftrightarrow8x^2-8x^2-100x-x=-300-3\\ \Leftrightarrow-101x=-303\\ \Leftrightarrow x=\dfrac{-303}{-101}=3\)

Đề câu d của bạn hình như sai dấu ý

sửa lại

.d. 3 - 4x (25 - 2x) = 8x ² + x - 300

câu bc hình bị lỗi

\(a,\dfrac{x-3}{x}=\dfrac{x-3}{x+3}\)\(\left(đk:x\ne0,-3\right)\)

\(\Leftrightarrow\dfrac{x-3}{x}-\dfrac{x-3}{x+3}=0\)

\(\Leftrightarrow\dfrac{\left(x-3\right)\left(x+3\right)-x\left(x-3\right)}{x\left(x+3\right)}=0\)

\(\Leftrightarrow x^2-9-x^2+3x=0\)

\(\Leftrightarrow3x-9=0\)

\(\Leftrightarrow3x=9\)

\(\Leftrightarrow x=3\left(n\right)\)

Vậy \(S=\left\{3\right\}\)

\(b,\dfrac{4x-3}{4}>\dfrac{3x-5}{3}-\dfrac{2x-7}{12}\)

\(\Leftrightarrow\dfrac{4x-3}{4}-\dfrac{3x-5}{3}+\dfrac{2x-7}{12}>0\)

\(\Leftrightarrow\dfrac{3\left(4x-3\right)-4\left(3x-5\right)+2x-7}{12}>0\)

\(\Leftrightarrow12x-9-12x+20+2x-7>0\)

\(\Leftrightarrow2x+4>0\)

\(\Leftrightarrow2x>-4\)

\(\Leftrightarrow x>-2\)