21^2/0.219 = 2013.69863
2 significant figures are the 20, so the answer is 2000

To solve this equation , we need to write it in quadratic form

To get the equation in quadratic form we replace x^2 with u

can be written as
, Replace u for x^2
So equation becomes

Now we factor the left hand side
-16 and -1 are the two factors whose product is +16 and sum is -17
(u-16) (u-1) = 0
u -16 = 0 so u=16
u-1 =0 so u=1
WE assume u = x^2, Now we replace u with x^2
Now take square root on both sides , x= +4 and x=-4
Now take square root on both sides , x= +1 and x=-1
So zeros of the function are -4, -1, 1, 4
3 divided by 85 is:
3/85
or in decimal form
0.03529411764
There are two ways to approach this.
Option #1:
Use the slope formula
.

That value is undefined, so the slope is undefined.
Option #2:
Because the two points have the same x-value, they will be vertically above/below one another. This means your line is a vertical line and the slope of a vertical line is undefined.
Either way, your slope is undefined.