(a+5)x^2-2(a+2)x+a=0
△=4(a+2)2-4a(a+5)=4a^2+16a+16-4a^2-20a = 16-4a < 0
∴ a > 4
ax^2-2(a-2)x+(a-5)=0
△=4(a-2)^2-4a(a-5)=4a^2-16a+16-4a^2+20a = 16+4a > 0
有两个不相等的实数根.
(a+5)x^2-2(a+2)x+a=0
△=4(a+2)2-4a(a+5)=4a^2+16a+16-4a^2-20a = 16-4a < 0
∴ a > 4
ax^2-2(a-2)x+(a-5)=0
△=4(a-2)^2-4a(a-5)=4a^2-16a+16-4a^2+20a = 16+4a > 0
有两个不相等的实数根.