\(-4x^2+20-16x+4x^2=-3\)

\(\left(-4x^2+4x^2\right)-16x=-3-20\)

\(0-16x=-23\)

\(x=\frac{23}{16}\)

CHÚC BN HX TỐT :))

\(-4x\left(x-5\right)-2x\left(8-2x\right)=-3\)

\(\Leftrightarrow-4x^2+20x-16x+4x^2=-3\)

\(\Leftrightarrow4x=-3\Leftrightarrow x=-\frac{3}{4}\)

-4x(x-5)-2x(8-2x)=-3

-4x^2+20x-16x+4x^2=-3

4x=-3

x=-3/4

<=>(-4)x(x-5)-2x(8-2x)=4x

=>4x=-3

=>x=\(-\frac{3}{4}\)

-4x(x-5)-2x(8-2x)=-3

=>-4x-(-20)-16-4x=-3

=>-4x+20-4x=-3+16

=>-4x-4x=13-20

=>-8x=-7

=>x=(-7):(-8)

=>x=0,875

-4x(x-5)-2x(8-2x)=3

-4x²-(-4)x5-2x(8-2x)=3

-4x²+20x-2x(8-2x)=3

-4x²+20x-2x8+2x2x=3

-4x²+20x-16x+4x²=3

(-4x²+4x²)+(20x-16x)=3

4x=3

x=3:4

x=3/4

ý, ghi nhầm -3 thành 3 rồi, kết 

kết quả đúng là -3/4

\(a.x=-0,6\)

\(c.x=-11,6\)

Pt nhju ak!!!

a) 2x+8≤ 0 

⇔2x≤-8

⇔x≤-4

b) 4x-7 ≥ 2x -5

⇔2x-12 ≥ 0

⇔2x≥12

⇔x≥6

c) (2x-8)(15-3x)>0

TH1: 2x-8>0 ⇒x>4

        15-3x>0⇒x<5 

TH2:  2x-8<0 ⇒x<4

        15-3x<0⇒x>5 (vô lí)

vậy 4<x<5

1) \(\Rightarrow10x-16-12x+15=12x-16+11\)

\(\Rightarrow14x=4\Rightarrow x=\dfrac{2}{7}\)

2) \(\Rightarrow4x^2+4x+1-4x^2+13x-3-15=0\)

\(\Rightarrow17x=17\Rightarrow x=1\)

3) \(\Rightarrow\left(3x-1\right)\left(2x-7+6x-5\right)=0\)

\(\Rightarrow\left(2x-3\right)\left(3x-1\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{3}{2}\\x=\dfrac{1}{3}\end{matrix}\right.\)

2: Ta có: \(\left(2x+1\right)^2-\left(4x-1\right)\left(x-3\right)-15=0\)

\(\Leftrightarrow4x^2+4x+1-4x^2+12x+x-3-15=0\)

\(\Leftrightarrow17x=17\)

hay x=1

-4x (x-5) - 2x (8-2x) = -3

= -4x^2 + 20x - 16x + 4x^2 = -3

= 20x - 16x = -3

= 4x = -3 

=> x = -3/4