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\(x^2-9-4\left(x+3\right)\)

\(=\left(x-3\right)\left(x+3\right)-4\left(x+3\right)\)

\(=\left(x+3\right)\left(x-3-4\right)\)

\(=\left(x+3\right)\left(x-7\right)\)

x2 - 9 - 4(x + 3)

= (x2 - 9) - 4(x + 3)

= (x2 - 32) - 4(x + 3)

= (x - 3) (x + 3) - 4(x + 3)

= (x + 3) (x -  3 - 4)

= (x + 3)  ( x - 7)

ko bít đúng ko !! 547467474856856856856835675743634634645765876976946426436

6 tháng 8 2016

\(x^2-9-4\left(x+3\right)\)

\(=\left(x-3\right)\left(x+3\right)-4\left(x+3\right)\)

\(=\left(x+3\right)\left(x-3-4\right)\)

\(=\left(x+3\right)\left(x-7\right)\)

6 tháng 8 2016

\(x^2-9-4\left(x+3\right)\)

\(=\left(x^2-9\right)-4\left(x+3\right)\)

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

\(=\left(x-3\right)\left(x+3\right)-4\left(x+3\right)\)

\(=\left(x+3\right)\left(x-3-4\right)\)

\(=\left(x+3\right)\left(x-7\right)\)

13 tháng 8 2021

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

\(=\left(x+3-4\right)\left(x+3+4\right)\)

\(=\left(x-1\right)\left(x+7\right)\)

17 tháng 9 2017

\(9\left(x-3\right)^2-4\left(x-1\right)^2=\left(3x-9\right)^2-\left(2x-2\right)^2\)

\(=\left[\left(3x-9\right)-\left(2x-2\right)\right]\left[\left(3x-9\right)+\left(2x-2\right)\right]\)

\(=\left(3x-9-2x+2\right)\left(3x-9+2x-2\right)\)

\(=\left(x-7\right)\left(5x-11\right)\)

8 tháng 8 2018

\(9\left(x-3\right)^2-4\left(x+1\right)^2\)

\(=\left[3\left(x-3\right)-2\left(x+1\right)\right].\left[3\left(x-3\right)+2\left(x+1\right)\right]\)

\(=\left(3x-9-2x-2\right)\left(3x-9+2x+2\right)\)

\(=\left(x-11\right)\left(5x-7\right)\)

8 tháng 8 2018

       \(9\left(x-3\right)^2-4\left(x+1\right)^2\)

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

\(=\left[3\left(x-3\right)\right]^2-\left[2\left(x+1\right)\right]^2\)

\(=\left[3x-9\right]^2-\left[2x+2\right]^2\)

\(=\left[3x-9-2x-2\right].\left[3x-9+2x+2\right]\)

\(=\left(x-11\right)\left(5x-7\right)\)

Chúc bạn học tốt.

7 tháng 11 2016

(x2+2x)2-2(x2+2x)-3

=(x2+2x)(x2+2x-2)-3

Đặt t=x2+2x ta có:

t(t-2)-3=t2-2t-3

=(t-3)(t+1)=(x2+2x-3)(x2+2x+1)

=(x-1)(x+3)(x+1)2

7 tháng 11 2016

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

=(x^2+2x)(x^2+2x-2)-3

=(x^2+2x)(x^2+2x-5)

4 tháng 1 2019

\(x^4+4x^3-2x^2-12x+9\)

\(=x^4+3x^3+x^3+3x^2-5x^2-15x+3x+9\)

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

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

\(=\left(x+3\right)\left(x^3+3x^2-2x^2-6x+x+3\right)\)

\(=\left(x+3\right)\left[x^2\left(x+3\right)-2x\left(x+3\right)+\left(x+3\right)\right]\)

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

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

8 tháng 9 2021

x2 + 6x + 9

= x2 + 2.3.x +  32

=  (x + 3)2

8 tháng 9 2021

`x^2 +6x+9`

`=x^2 + 2 . x . 3 + 3^2`

`= (x+3)^2`

23 tháng 10 2018

\(x^2-7x+9\)

\(=x^2-2.x.\frac{7}{2}+\left(\frac{7}{2}\right)^2-\frac{13}{4}\)

\(=\left(x-\frac{7}{2}\right)^2-\left(\frac{\sqrt{13}}{2}\right)^2\)

\(=\left(x-\frac{7}{2}-\frac{\sqrt{13}}{2}\right)\left(x-\frac{7}{2}+\frac{\sqrt{13}}{2}\right)\)

\(=\left(x-\frac{7+\sqrt{13}}{2}\right)\left(x-\frac{7-\sqrt{13}}{2}\right)\)