y=½x² - 6x + 21 怎么弄成 =½(x-6)x² +3

问题描述:

y=½x² - 6x + 21 怎么弄成 =½(x-6)x² +3

y=½x² - 6x + 21
=1/2(x²-12x)+21
=1/2(x-6)²-6²*1/2+21
=1/2(x-6)²+3