\(\left(3x-2\right)\left(x^2-4x+5\right)\)

\(=3x^3-12x^2+15x-2x^2+8x-10\)

\(=3x^3-14x^2+23x-10\)

\(a.3\left(x^2-2x+1\right)-3x^2+15x-2=0\)

\(3x^2-6x+3-3x^2+15x-2=0\)

\(9x+1=0\)

\(x=-\frac{1}{9}\)

\(b.4x^2-12x+9=0\)

\(4x^2-6x-6x+9=0\)

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

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

\(\Rightarrow\orbr{\begin{cases}2x-3=0\\x-3=0\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=\frac{3}{2}\\x=3\end{cases}}\)

\(c.\left(2x-3\right)^2-\left(x+5\right)^2=0\)

\(\left(2x-3-x-5\right)\left(2x-3+x+5\right)=0\)

\(\left(x-8\right)\left(3x+2\right)=0\)

\(\Rightarrow\orbr{\begin{cases}x-8=0\\3x+2=0\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=8\\x=-\frac{2}{3}\end{cases}}\)

d) \(\frac{4x^2-12x+9}{9-4x^2}=-\frac{\left(2x+3\right)^2}{\left(2x-3\right)\left(2x+3\right)}=\frac{2x+3}{2x-3}\)

D = x - x² + 3

D = - x² + x + 3

D = - ( x² - x - 3 )

D = - [ x² - 2 . x . 1 / 2 + ( 1 / 2 )² - ( 1 / 2 )² - 3 ]

D = - [ ( x - 1 / 2 )² - 13 / 4 ]

D = - ( x - 1 / 2 )² + 13 / 4 \(\le\)13 / 4

Dấu " = " xảy ra \(\Leftrightarrow\)x - 1 / 2 = 0

                             \(\Rightarrow\)x              = 1 / 2

Max D = 13 / 4 \(\Leftrightarrow\)x = 1 / 2

D=x-x^2+3

D= -[x^2 -x +1/4 ] + 13/4 

D=-(x-1/2)^2 +13/4 

Vì -(x-1/2)^2<=0 => D<=13/4

Dấu = xảy ra <=> x-1/2=0 <=> x=1/2

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

\(=4\left(x+2\right)^2\)

Học tốt

\(x^3-2x^2+x-xy^2\)

\(=x\left(x^2-2x+1-y^2\right)\)

\(=x\left[\left(x-1\right)^2-y^2\right]\)

\(=x\left(x-1-y\right)\left(x-1+y\right)\)

Câu a ko rõ đề bài lắm

\(b.\left(x+2\right)\left(x+2-x+2\right)=0\)

\(\left(x+2\right).4=0\)

\(\Rightarrow x+2=0\)

\(x=-2\)

Phân tích các đa thức sau thành nhân tử ... c) 6x(x+y)^2+3x^2y(x+y). 2: .... x³ - 5x + 8x - 4=x² . x -5x + 8x -2² = (x² - 2²) . (x -5x + 8x )=(x-2) . (x+2) . 4x. x³ - 9x² ..... Phân tích các đa thức sau thành nhân tử : a,x^3+5x^2+8x+4 b, x^3-9x^2+6x+16 .

\(a.=x^2\left(x-y\right)-25\left(x-y\right)\)

\(=\left(x-5\right)\left(x+5\right)\left(x-y\right)\)

\(b.=\left(b-a\right)\left(b+a\right)-4\left(b-a\right)\)

\(=\left(b+a-4\right)\left(b-a\right)\)

Ta có a(b+c)^2 +b(c+a)^2+c(a+b)^2 =4abc

ab^2+ac^2+2abc+ba^2bc^2+2abc+ca^2+cb^2+2abc=4abc

ab^2+ac^2+bc^2+ba^2+cb^2+ca^2+2abc=0

(ab^2+abc)+(ac^2+abc)+(bc^2+cb^2)+(a^2b+a^2c)=0

ab(b+c)+ac(b+c)+bc(b+c)+a^2(b+c)=0

(b+c)(ab+ac+bc+a^2)=0

(b+c)(a+b)(a+c)=0

*th1:b+c=0=> b=-c

=> b^2017 +c^2017 =0 

mà a^2017 +b^2017 +c^2017=1

=>a^2017=1 => a=1 

thay vào A rồi dc A=1 

các th khác tương tự

\(C=x^2-4x+8\)

\(C=x^2-4x+4+4\)

\(C=\left(x-4\right)^2+4\ge4\)

Dấu bằng xảy ra 

\(\Leftrightarrow x-4=0\)

\(\Leftrightarrow x=4\)

Vậy Min A = 4 <=> x= 4

giải lun câu này dùm ik: D= x- x^2+ 3. Tìm GTNN hoặc GTLN