# Thread: Need some help with part A

1. ## Need some help with part A

2. Let P=(x, y) be a point on the graph of y = x^2 - 8.
a) Express the distance of d from P to the point (0, -1) as a function of x.
b) What is d if x = 0?
c) What is d if x = -1?
d) Use a graphing utility to graph d = d (x).
e) For what values of x is d smallest?

a) d(x) = √x^4-13x^2+49
b) d(0)=7
c) d(-1)= √37 ... is similar to ... 6.08
d) Graph d(x) = √x^4-13x^2+49
e) D is the smallest when x ... is similar to ... -2.55 or x ... is similar to ... 2.55

I can do all of them but part “A” can someone help me figure out how to find out part A?

and how do you do a "... is similar to ..." sign on here?

2. Originally Posted by Robthebear
2. Let P=(x, y) be a point on the graph of y = x^2 - 8.
a) Express the distance of d from P to the point (0, -1) as a function of x.
[...]
I can do all of them but part “A” can someone help me figure out how to find out part A?

and how do you do a "... is similar to ..." sign on here?
$\sim$ or $\approx$ or simply ~.

As to part a: The distance between points with coordinates (a,b) and (c,d) is
$\sqrt{(a-c)^2 + (b-d)^2}$.
Now in this case, $a = x, b = y = x^2-8, \, c = 0,\, d = -1$.
Insert these expressions in the distance formula and you are done.

3. Thank you for the help.
Robert