The equation - 5x² + 72x + 378 models the number of students enrolled in a school where x is the number of years since the school first opened in 1990. In which year were 502 students enrolled?
a 1996
b 1992
c 1998
d 2002

Question

The equation - 5x² + 72x + 378  models the number of students enrolled in a school where x is the number of years since the school first opened in 1990.  In which year were 502 students enrolled? 
a 1996
b 1992
c 1998
d 2002

crashonce · Answer

so to start, write the quadratic equation and factor out the minus sign
what do you get?

crashonce · Answer

then you can factor it to -(5x-62)(x-2)

crashonce · Answer

solve that and you will get -6/5 and 2
Now we can't have -6/5 years so the only viable option is 2

crashonce · Answer

so I would say 1992

anonymous · Answer

if you enter a number for f(x)=5x^2+72x+378
entering 1 = 455
entering 2 = 542
so 1990+2 = 1992

crashonce · Answer

thats better