(x² - 2x) - (2x - 56)
= x² - 2x - 2x + 56
= x² - 4x + 4 + 52
= (x - 2)² + 52
> 0
所以 x² - 2x > 2x - 56
x的平方-2x与2x-56比大小?
(x² - 2x) - (2x - 56)
= x² - 2x - 2x + 56
= x² - 4x + 4 + 52
= (x - 2)² + 52
> 0
所以 x² - 2x > 2x - 56