Question

Giúp mình với ạ

Answer 1

2B

a) 255 - (4 - x)²

= 15² - (4 - x)²

= (15 - 4 + x)(15 + 4 - x)

= (13 + x)(19 - x)

b) (2y + 5)² - 9x²

= (2y + 5)² - (3x)²

= (2y + 5 - 3x)(2y + 5 + 3x)

c)  (3y - 4)² - (2y + 5)²

= (3y - 4 - 2y - 5)(3y - 4 + 2y + 5)

= (y - 9)(5y + 1)

d) (z - 3y)³ - (z + 3y)³

= (z - 3y - z - 3y)[(z - 3y)² + (z - 3y)(z + 3y) + (z + 3y)²]

= -6y(z² - 6yz + 9y² + z² - 9y² + z² + 6yz + 9y²)

= -6y(3z² + 9y²)

= -18y(z² + 3y²)

Answer 2

2B

a)

\(=15^2-\left(4-x\right)^2\\ =\left(15-4+x\right)\left(15+4-x\right)\\ =\left(9+x\right)\left(19-x\right)\)

b)

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

c)

\(=\left(3y-4-2y-5\right)\left(3y-4+2y+5\right)\\ =\left(y-9\right)\left(5y+1\right)\)

d)

\(=\left(z-3y-z-3y\right)\left(z^2-6zy+9y^2+z^2+6zy+9y^2\right)\\ =-6y\left(2z^2+18y^2\right)\)