ta có :

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

bạn ơi  bạn viết sai đề có đề nào viết  thế này đâu?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????

Uchiha Itachi

a) \(81-\left(3x+2\right)^2=9^2-\left(3x+2\right)^2=\left(9-3x-2\right)\left(9+3x+2\right)=\left(7-3x\right)\left(11+3x\right)\)

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

\(=\left(5x-5\right)\left(9x-3\right)=15\left(x-1\right)\left(3x-1\right)\)

c) \(9\left(x-5y\right)^2-16\left(x+y\right)^2=\left[3\left(x-5y\right)-4\left(x+y\right)\right]\left[3\left(x-5y\right)+4\left(x+y\right)\right]\)

\(=\left(-x-19y\right)\left(7x-11y\right)\)

a. x² - 11 = \(x^2-\left(\sqrt{11}\right)^2=\left(x-\sqrt{11}\right)\left(x+\sqrt{11}\right)\)

b. x² - 5 = \(x^2-\left(\sqrt{5}\right)^2=\left(x-\sqrt{5}\right)\left(x+\sqrt{5}\right)\)

c. x² - 7 = \(x^2-\left(\sqrt{7}\right)^2=\left(x+\sqrt{7}\right)\left(x-\sqrt{7}\right)\)

Em cảm ơn ạ<33

a, \(x^2-4-3\left(x-2\right)=\left(x-2\right)\left(x+2\right)-3\left(x-2\right)=\left(x-1\right)\left(x-2\right)\)

b, \(x^2-xy+5y-25=\left(x-5\right)\left(x+5\right)-y\left(x-5\right)=\left(x+5-y\right)\left(x-5\right)\)

c, \(x^3+x^2-2x-8=\left(x-2\right)\left(x^2+2x+4\right)+x\left(x-2\right)=\left(x-2\right)\left(x^2+3x+4\right)\)

d, \(x^3-4x^2-8x+8=\left(x+2\right)\left(x^2-2x+4\right)-4x\left(x+2\right)=\left(x^2-6x+4\right)\left(x+2\right)\)

Trả lời:

1, x² - 4 - 3 ( x - 2 )

= ( x² - 4 ) - 3 ( x - 2 )

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

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

= ( x - 2 ) ( x - 1 )

2, x² - xy + 5y - 25

= ( x² - 25 ) - ( xy - 5y )

= ( x - 5 ) ( x + 5 ) - y ( x - 5 )

= ( x - 5 ) ( x + 5 - y )

3, x³ + x² - 2x - 8

= ( x³ - 8 ) + ( x² - 2x )

= ( x - 2 ) ( x² + 2x + 4 ) + x ( x - 2 )

= ( x - 2 ) ( x² + 2x + 4 + x )

= ( x - 2 ) ( x² + 3x + 4 )

4, x³ - 4x² - 8x + 8 

= ( x³ + 8 ) - ( 4x² + 8x )

= ( x + 2 ) ( x² - 2x + 4 ) - 4x ( x + 2 )

= ( x + 2 ) ( x² - 2x + 4 - 4x )

= ( x + 2 ) ( x² - 6x + 4 )

xin lỗi em lớp 3 :>>>>

𝑥2−3𝑥+2

(x-5)^2

k nhé tó k lại