2r² - 8ar + 5a² = 0 求化简 要具体步骤

2r² - 8ar + 5a² = 0 求化简 要具体步骤
2r² - 8ar + 5a² = 0 求化简 要具体步骤

2r² - 8ar + 5a² = 0 求化简 要具体步骤
原式=2(r^2-4ar+4a^2-4a^2)+5a^2=0
即2(r-2a)^2+5a^2-8a^2=0
(r-2a)^2=3a^2/2
所以r-2a=±√6a/2
r=2a±√6a/2