Question

Làm bài 2 , giúp

Answer 1

Bài 2

a) (x - 3)(x + 7) - (x + 5)(x - 1)

= x² + 7x - 3x - 21 - x² + x - 5x + 5

= -16

b) (4x² + y²)(2x + y)(2x - y)

= (4x² + y²)(4x² - y²)

= 16x⁴ - y⁴

c) (3a + 1)² + (2 - 3a)(2 + 3a)

= 9a² + 6a + 1 + 4 - 9a²

= 6a + 5

d) (x + y)² + (x - y)² + 2(x - y)(x + y) 

= (x + y + x - y)²

= (2x)²

= 4x²

e) 5x² - (2x + 1)(x - 2) - x(3x + 3) + 7

= 5x² - 2x² + 4x - x + 2 - 3x² - 3x + 7

= 9

f) (x + 2)³ - (x - 1)(x² + x + 1) - 6(x - 1)²

= x³ + 6x² + 12x + 8 - x³ + 1 - 6x² + 12x - 6

= 24x + 3