Given equation is
.
Now we need to find about what are the key aspects of the graph of
, where b is a real number.
We know that square of any number is always positive.
then
must be a positive number.
So that means for any real number b, as the value of b increases then graph of f(x) shifts downward by
units as compared to the graph of parent function 
For this case we have that by definition, the quadratic formula is:
A quadratic equation is of the form:

Option A: This equation can be solved without the quadratic formula

Option B:
This equation is not as easy to solve by factoring or as option A. We can use the quadratic formula.
Option C:

Similarly, this equation can be solved with the quadratic formula
Option D:

In this factored equation we can see that the roots are

Answer:
Option B, C
It is a
9/4=2.25*2=4.5
Hope it helps :)
6/21 + 7/21 = 13/21 of the lawn was mowed?