已知y<3 化简 (y+3)×√y²-6y+9

问题描述:

已知y<3 化简 (y+3)×√y²-6y+9

(y+3)×√y²-6y+9
=(y+3)×√(y-3)²
= (y+3)×|y-3|
=(y+3)(3-y)
=9-y²