Ta có: \(5x\left(12x+7\right)-3x\left(20x-5\right)=-100\)

\(\Leftrightarrow60x^2+35x-60x^2+15x=-100\)

\(\Leftrightarrow50x=-100\)

hay x=-2

   \(5x.\left(12x+7\right)-3x.\left(20x-5\right)=-100\)

\(5x.12x+5x.7+\left(-3x\right).20x+\left(-3x\right).\left(-5\right)=-100\)

                            \(60x^2+35x-60x^2+15x=-100\)

                      \(\left(60x^2-60x^2\right)+\left(35x+15x\right)=-100\)

                                                              \(50x=-100\)

                                                                  \(x=\left(-100\right):50\)

                                                                  \(x=-2\)

                                                           Vậy:\(x=-2\)

\(5x\left(12x+7\right)-\left(3x+1\right)\left(20x-5\right)=-100\\ 60x^2+35x-\left(60x^2-15x+20x-5\right)=-100\\ 60x^2+35x-60x^2+15x-20x+5=-100\\ 30x=-105\\ \Rightarrow x=\frac{-7}{2}\)

Vậy \(x=\frac{-7}{2}\)

\(5x\left(12x+7\right)-\left(3x+1\right)\left(20x-5\right)=-100\)

\(\Leftrightarrow60x^2+35x-\left(60x^2-15x+20x-5\right)=-100\)

\(\Leftrightarrow60x^2+35x-60x^2+15x-20x+5=-100\)

\(\Leftrightarrow30x=-100-5\)

\(\Leftrightarrow30x=-105\)

\(\Leftrightarrow x=\frac{-105}{30}=\frac{-7}{2}\)

\(5x\left(12x+7\right)-3x\left(20x-5\right)=-100\)

\(\Leftrightarrow60x^2+35x-60x^2+15x=-100\)

\(\Leftrightarrow50x=-100\)

hay x=-2

a: =>1,5x^2-2x+1,2x-1,5x^2>=0,32

=>-0,8x>=0,32

=>x<=4

b: =>60x^2+35x-60x^2+15x<=-100

=>50x<=-100

=>x<=-2

a)\(0,5x\left(3x-4\right)+1,5x\left(0,7-x\right)\ge0,32\)

\(\Leftrightarrow1,5x^2-2+1,05-1,5x^2\ge0,32\)

\(\Leftrightarrow1,5x^2-1,5x^2-2+1,05\ge0,32\)

\(\Leftrightarrow-0,95\ge0,32\)(vô lí)

Vậy bất phương trình vô nghiệm

b)\(5x\left(12x+7\right)-3x\left(20x-5\right)\le-100\)

\(\Leftrightarrow60x^2+35x-60x^2+15x\le-100\)

\(\Leftrightarrow50x\le-100\)

\(\Leftrightarrow x\le-2\)

Vậy bất phương trình có nghiệm là \(S=\left\{xIx\le-2\right\}\)

a) 5x(12x + 7) - 3x(20x - 5) = -100

<=> 60x² + 35x - 60x² + 15x = -100

<=> 50x = -100

<=> x = -2

b) 0,6x(x - 0,5) - 0,3x(2x + 1,3) = 0,138

<=> 0,6x² - 0,3x - 0,6x² - 0,39x = 0,138

<=> -0,69x = 0,138

<=> x = -0,2

c) 4x(3x - 7) - 6(2x² - 5x + 1) = 12

<=> 12x² - 28x - 12x² + 30x - 6 = 12

<=> 2x - 6 = 12

<=> 2x = 18

<=> x = 9

3x(x-2) - 3x^2 =1

3x^2 - 6x - 3x^2 = 1

-6x =1

x= -1/6

-----------------------------------------

5x(12x+7)-3x(20x-5) = -100

60x^2 + 35x - 60x^2 + 15x = -100

50x =-100

x=-2

Cám ơn bạn

a)\(60x^2+35x-60x^2+15x=100\)

  35x+15x=100

  50x=100   =>x=2

b)\(10x^2-35x+16x-10x^2=5\)

  -35x+16x=5

   -19x=5    =>x=-5/19

a)

  35x+15x=100

  50x=100   

=>x=2

b)

  -35x+16x=5

   -19x=5   

=>x=-5/19