<=> [(x + 2)(x + 5)][(x + 3)(x + 4) - 24 = (x² + 7x + 10) (x² + 7x + 12) - 24 (1)

đặt x² + 7x + 11 = t

=> ( 1 ) <=> (t - 1)(t + 1) - 24 = t² - 1 - 24 = t² - 25 = (t - 5)(t + 5)

=> (x² + 7x + 11 - 5) (x² + 7x + 11 + 5) = (x² + 7x + 6) (x² + 7x + 16) (x + 1) (x + 6) (x² + 7x + 16)

chúc you học tốt!! ^^

ok mk nhé!! 4545454353434636565454676345345346654767567567587676345346334534534565646756

a, \(\left(4x+5\right)^2=\left(4x+5\right)\left(4x+5\right)=\left[\left(4x+5\right)4x\right]+\left[\left(4x+5\right)5\right]=4x^2+20x+25\)

b, \(\left(5x-2\right)^2=\left(5x-2\right)\left(5x-2\right)=\left[\left(5x-2\right)5x-\left(5x-2\right)2\right]=5x^2-10x+25\)

b, \(8^2-12x^2=\left(8^2-12x^2\right)\left(8^2+12x^2\right)\)

đúng ko :) 

@No name: Bị sai rồi nhé, a,b,c sai hết  :>

a) ( 4x + 5 )² 

= ( 4x )² + 2.4x.5 + 5² 

= 16x² + 40x + 25 

b) ( 5x - 2 )² 

= ( 5x )² - 2.5x.2 + 2² 

= 25x² - 20x + 4 

c) 8² - 12x² 

= 64 - 12x² 

= ( V8 - V12x )( V8 + V12x ) 

Ta có \(x^4+y^4+\left(x+y\right)^4=\left(x^2+y^2\right)^2-2x^2.y^2+\left(x+y\right)^4\)

\(=\left[\left(x+y\right)^2-2xy\right]^2-2x^2.y^2+\left(x+y\right)^4\)\(=\left(x+y\right)^4-4xy\left(x+y\right)^2+4x^2y^2-2x^2y^2+\left(x+y\right)^4\)

\(=2\left(x+y\right)^4-4xy\left(x+y\right)^2+2x^2y^2\)\(=2\left[\left(x+y\right)^4-2.xy.\left(x+y\right)^2+\left(xy\right)^2\right]\)

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

Không phân tích thành nhân tử được nhé :(

x⁸+3x⁴+4

= x⁸+4x⁴+4-x⁴

= (x⁴+2)²-(x²)²

= (x⁴+2-x²).(x⁴+2+x²)

\(x^8+3x^4+4=(x^8+3x^4)+4=x^4(x^2+3)+4=(x^2+3)(x^4+4)\)

Ta có 

\(x^4+6x^2+25=\left(x^4+10x^2+25\right)-4x^2\)

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

\(3x^4+4x^2+28x+5=\left(x^2-2x+5\right)\left(3x^2+6x+1\right)\)

\(\Rightarrow P\left(x\right)=x^2-2x+5\)

\(\Rightarrow P\left(1\right)=1-2+5=4\)

khó thế????

a: x²+4x+3

=x²+x+3x+3

=(x²+x)+(3x+3)

=x(x+1)+3(x+1)

=(x+1)(x+3)

\(x^4-5x^2+4=x^4-x^2-4x^2+4=x^2\left(x^2-1\right)-4\left(x^2-1\right)=\left(x^2-4\right)\left(x^2-1\right)\)

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

Ta có : x⁴ - 5x² + 4

= x⁴ - x² - 4x² + 4

= x²(x² - 1) + (4x² - 4) 

= x²(x² - 1) + 4(x² - 1)

= (x² - 1)(x² + 4) 

P = x³ - x² - x² + x + 4x - 4 = x²(x-1) - x(x - 1) + 4(x-1) = (x - 1)(x² - x + 4).

Hết, đa thức bậc 2:  x² - x + 4 ko phân tích được thành nhân tử.