用配方法解y=3x^2-2x+1 和y=1/2x^2-x-3_数学解答

用配方法解y=3x^2-2x+1 和y=1/2x^2-x-3

人气：478 ℃　时间：2020-07-03 14:48:06

解答

y=3x^2 -2x+1
=3[x^2 -(2/3)x]+1
=3[x^2 -(2/3)x+(1/9)-(1/9)]+1
=3[x-(1/3)]^2 +(2/3)
y=(1/2)x^2 -x-3
=(1/2)[x^2 -2x-6]
=(1/2)[x^2 -2x+1-7]
=(1/2)(x-1)^2 -(7/2)