Marc L. answered 11/17/20
Scored an 800 on SAT Math section
so for this we will use the discriminant to find what values of a and c give imaginary roots:
b2-4ac; 64-4ac<0, 64<4ac, 16<ac so we can say a=1 and c=17
x2-8x+17=0
x=(8±sqrt(64-68))/2, x=(8±sqrt(-4))/2, x=(8±2i)/2, x=4±i