K kokshen3414 Feb 2019 2 0 US Feb 9, 2019 #1 Need help with 11)，12） Sent from my CPH1819 using Tapatalk

P Plato MHF Helper Aug 2006 22,472 8,642 Feb 9, 2019 #2 kokshen3414 said: Need help with 11)，12） Sent from my CPH1819 using Tapatalk Click to expand... Do not ever post the same question twice. The quadratic $ax^2+bx+c=0$ has two real roots if and only if $b^2-4ac>0$. That is the idea for both 11 & 12.

kokshen3414 said: Need help with 11)，12） Sent from my CPH1819 using Tapatalk Click to expand... Do not ever post the same question twice. The quadratic $ax^2+bx+c=0$ has two real roots if and only if $b^2-4ac>0$. That is the idea for both 11 & 12.