Posted by Rebekah on Tuesday, September 25, 2012 at 9:23pm.
#1: f(x) = x^24x
find vrtex, axis ofsym, yint, xint if any, domain, range, where increasing and decreasing.
I got.... vertex: 2,4
axis of sym: x=2
D= (infinity, infnity)
range= [4,infinity)
im stuck of the intercepts because when i plug i 0 for x i get yint of 0 but the graph doesnt show that.
Am i doing the completingthe square wrong
I got (x^22)^2 + 4
#2 Same requirements as the first question
f(x)= x^2 + 6x +9
I got... vertex: (3,18)
axis of sym: x=3
Domain= (infinity, infinity)
Range= [18, infinity)
yint (0,9)
xint idk???
After completing the square I got:
(x+3)^2 + 18
Also a question, how do you know if there is an x or y int without drawing the graph because my graph des not show a xint but the equation does?
Thanks!

Precalc  Scott, Wednesday, September 26, 2012 at 1:14pm
you seem to be finding the axis of symmetry okay
when you plugged in to find the vertex in #1, there is an error (should be 2,4)
__ this also affects the range
completing the square should be:
f(x) = (x  2)^2  4
(x  2)^2 = x^2  4x + 4
so you need to subtract out the extra 4 that you add when using the binomialsquare
looks like a similar error on the vertex for #2 __ also in the range
#2 is already a perfect square, so completing the square went amiss
finding intercepts without a picture means individually (not at the same time) substituting zero for x and y, and solving for the other value
for quadratics in x, there will ALWAYS be a yintercept
depending on the values of a, b, and c; there may be two, one , or no xintercepts
the discriminant (b^2  4ac) shows the nature of the roots (xintercepts)
Answer This Question
Related Questions
 Check my precalc?  #1: f(x) = x^24x find vrtex, axis ofsym, yint, xint if ...
 Quadractic Functions  Please check my answers. Find the xintercepts (if any) ...
 algebra  Can someone check my answers please and if Im wrong please explain. 1...
 College Algebra  Here is the whole question... I have figured most of it out ...
 Calculus  find the intervals where the function is increasing and the intervals...
 Math (Domain and range)  Evaluate the function f(x)={9x+5, x<0 {9x+6, x>(...
 Precalculus  Can somebody help me wit this? Find the range and the domain of: ...
 algebra  Can someone check my answers on exploring conic sections? 1. Graph x2...
 College algebra  Given the following quadratic equation find. a) the vertex b) ...
 college algebra  Given the following quadratic equation, find;? a. the vertex b...
More Related Questions