a/ 3x(12x-4)-9x(4x-3)

=36x²-12x-36x²+27x

=(36x²-36x²)-12x+27x

=15x

b/ x(5-2x)+2x(x-1)

=5x-2x²+2x²-2x

=(5x-2x)-(-2x²+2x²)

=3x

c/ 5x(12x+7)-3x(20x-5)

=60x²+35x-60x²+15x

=(60x²-60x²)+(35x+15x)\

=50x

d/ 3x(2x-7)+2x(5-3x)

=6x²-21x+10x-6x²

=(6x²-6x²)+(10x-21x)

=-11x

e/ đề sai hay sao ý ra số to lắm @@

a) (12x-5)(4x-1)+(3x-7)(1-16x)

= (48x^2 - 12x - 20x + 5) + (3x - 48x^2 - 7 + 112x)

= 48x^2 - 12x - 20x + 5 +3x - 48x^2 -7 + 112x

= 83x-2

những phần sau bạn cứ làm tương tự theo cách nhân đa thức với đa thức và phá ngiawcj là ra nha :0))

sao ko làm hết ra

a: =>2x^2-2x+2x-2-2x^2-x-4x-2=0

=>-5x-4=0

=>x=-4/5

b: =>6x^2-9x+2x-3-6x^2-12x=16

=>-19x=19

=>x=-1

c: =>48x^2-12x-20x+5+3x-48x^2-7+112x=81

=>83x=83

=>x=1

\(16x^3-12x^2+3x-7=0\)

\(\Leftrightarrow16x^3-16x^2-3x^2+3x+7x^2-7=0\)

\(\Leftrightarrow16x^2\left(x-1\right)-3x\left(x-1\right)+7\left(x-1\right)\left(x+1\right)=0\)

\(\Leftrightarrow16x^2\left(x-1\right)-3x\left(x-1\right)+\left(x-1\right)\left(7x+7\right)=0\)

\(\Leftrightarrow\left(x-1\right)\left(16x^2-3x+7x+7\right)=0\)

\(\Leftrightarrow\left(x-1\right)\left(16x^2+4x+7\right)=0\)

<=> x - 1 = 0 

<=> x = 1

\(\Leftrightarrow16x^3-16x^2+4x^2-4x+7x-7=0\)

\(\Leftrightarrow16x^2.\left(x-1\right)+4x.\left(x-1\right)+7.\left(x-1\right)=0\)

\(\Leftrightarrow\left(x-1\right).\left(16x^2+4x+7\right)=0\)

Ta có \(16x^2+4x+7=\left(4x\right)^2+2.4x.\frac{1}{2}+\frac{1}{4}+\frac{27}{4}\)

\(=\left(4x+\frac{1}{2}\right)^2+\frac{27}{4}>0\)

nên \(\left(x-1\right).\left(16x^2+4x+7\right)=0\)

\(\Leftrightarrow x-1=0\)

\(\Rightarrow x=1\)

\(16x^3-12x^2+3x-7=0\)

\(16x^3-16x^2+4x^2-4x+7x-7=0\)

\(16x^2\left(x-1\right)+4x\left(x-1\right)+7\left(x-1\right)=0\)

\(\left(x-1\right)\left(16x^2+4x+7\right)=0\)

        Vì \(0< 16x^2+4x+7\)

\(\Rightarrow x-1=0\)

\(\Rightarrow x=1\)

= 16x³ -16x² + 4x² - 4x + 7x - 7

= 16x²(x-1)+4x(x-1)+7(x-1)

=(x-1)(16x²+4x+7)