Chứng minh rằng

----- Nội dung dịch tự động từ ảnh -----
Bài 12: Chứng minh rang:

1) A = n(3/n + 5)
B = n(3/n - 2)
C = (2/n - 1)(n - 2)

2) (8x - 3)(3x - 2) - (4x - 7)(x + 5) = 0
(7x + 7)(2x - 3)(x - 2) = 81

3) 1) (3x - 1) = 7(2x - 1) + 9(3x - 4) = 30
2) 4(x + 2) - 7(2x - 1) = 11
3) (2x + 5)(x - 4)

4) 3x(3x - 2) - 3(3x - 1)(x - 2)

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

6) (2x + 5)(x - 4)

7) (x - 1)(3x - 1) - 33

8) (3x - 1)(3x - 2) = 81