Question

Thực hiện các phép tính:

a) -7x²(3x - 4y)           b) (x - 3)(5x - 4)

c) (2x - 1)²           d) (x + 3)(x - 3)

Answer 1

Tham khảo

a)

-7x²(3x - 4y)

= -7x².3x + 7x^2ư.4y

= -21x² + 28x²y

b)

(x - 3)(5x - 4)

= x.5x - x.4 - 3.5x + 3.4

= 5x² - 4x - 15x + 12

= 5x² - 19x + 12

c)

(2x - 1)² = 4x² - 4x + 1

d)

(x + 3)(x - 3) = x² - 3² = x² - 9

Answer 2

a, = -21x³ +28x²y

b, = 5x² -4x -15x +12

= 5x² -19x +12

c, =x² -9

Answer 3

a)-21x³+28x²y

b)5x²-19x+12

c)4x²-4x+1

d)x²-9