Question

1. Phân tích đa thức thành nhận tử

a) 5ay-3bx + ax -15by

b)\(x^3+x^2-x-1\)

c)\(\left(2a+b\right)^2-\left(2b+a\right)^2\)

d) \(\left(8a^3-27b^3\right)-2a\left(4a^2-9b^2\right)\)

giúp mk vs ~~~please~~~

Answer 1

a) 5ay - 3bx + ax - 15by

= (5ay + ax) - (3bx + 15by)

= a (5y + x) - 3b (x + 5y)

= (5y + x) (a - 3b)

b) x^3 + x^2 - x - 1

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

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

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

c) (2a + b)^2 - (2b + a)^2

= 4a^2 + 4ab + b^2 - 4b^2 - 4ab - a^2

= 3a^2 - 3b^2

= 3 (a^2 - b^2)

d) (8a^3 - 27b^3) - 2a (4a^2 - 9b^2)

= 8a^3 - 27b^3 - 8a^3 + 18ab^2

= 27b^3 + 18ab^2

= 9b^2 (3b + 2a)