Question

Có ai có thể giúp mk bài này đc ko? Thanks nhiều

Answer 1

Bài 1:

a, 4x²+6x=2x(2x+3)

b, 12x(x-2y)-9y(x-2y)=3(x-2y)(4x-3y)

c, 3x³-6x²+3x=3x(x²-2x+1)=3x(x-1)²

d, 2x³-2xy²+12x²+18x=2x(x²-y²)+2x(6x+9)=2x(x²+6x+9-y²)

  =2x[(x+3)²-y² ]=2x(x+y+3)(x-y+3)

Bài 2:

a, 5x(x-1)+10x-10=0 <=> 5x(x-1)+10(x-1)=0  <=> 5(x-1)(x+2)=0

   \(\Leftrightarrow\orbr{\begin{cases}5\left(x-1\right)=0\\x+2=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=1\\x=-2\end{cases}}}\)

b,(x+2)(x+3)-2x=6  <=> (x+2)(x+3)-2(x+3)=0  <=> (x+3)(x+2-2)=0  <=> x(x+3)=0 

\(\Leftrightarrow\orbr{\begin{cases}x=0\\x+3=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=0\\x=-3\end{cases}}}\)

c, \(\left(x-1\right)\left(x-2\right)-2=0\Leftrightarrow x^2-3x+2-2=0\Leftrightarrow x\left(x-3\right)\)\(\Leftrightarrow\orbr{\begin{cases}x=0\\x-3=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=0\\x=3\end{cases}}}\)

Answer 2

Bài 3

 a, \(x^4y+3x^3y^2+3x^2y^3+xy^4=xy\left(x^3+3x^2y+3xy^2+y^3\right)=xy\left(x+y\right)^3\)

 b, \(x^4+4=x^4+4x^2+4-4x^2=\left(x^2+2\right)-\left(2x\right)^2=\left(x^2+2x+2\right)\left(x^2-2x+2\right)\)

hình học 

Bài 1 \(\widehat{D}=360^o-\widehat{A}-\widehat{B}-\widehat{C}=360^o-50^o-120^o-90^o=100^o\)

Bài 2 \(Tc:\widehat{C}+\widehat{D}=360^o-\widehat{A}-\widehat{B}=360^o-50^o-110^o=200^o\)

\(\Rightarrow\widehat{C}=200^o-\widehat{D}\)mà \(\widehat{C}=3\widehat{D}\)nên ta có \(3\widehat{D}=200^o-\widehat{D}\Leftrightarrow4\widehat{D}=200^o\Leftrightarrow\widehat{D}=50^o\Rightarrow\widehat{C}=3.50^o=150^o\)

Bài 4 \(\widehat{C}+\widehat{D}=360^o-90^o-110^o=160^o\)

Áp dụng dãy tỉ số bằng nhau

\(\frac{\widehat{C}}{3}=\frac{\widehat{D}}{5}=\frac{\widehat{C}+\widehat{D}}{3+5}=\frac{160^0}{8}=30^o\)

\(\Rightarrow\frac{\widehat{C}}{3}=30^o\Rightarrow\widehat{C}=30^o.3=90^o\Rightarrow\widehat{D}=160^o-90^o=70^o\)