If ax2+bx+c, a,b,c∈R,a<0 has no real zeros and a−b+c<0, then the value of ac
=0
>0
<−1
<0
f(x)=ax2+bx+c
f(−1)=a−b+c<0⇒a<0
f(0)=0+0+c<0
⇒ac>0