SOLUTION: I'm trying to find the x-intercepts for the equation Y=16-4x^2. What I've tried to do is change the y to 0, and factor the rest of the equation, but I keep getting left with a 4 t

Question 211249This question is from textbook
: I'm trying to find the x-intercepts for the equation Y=16-4x^2. What I've tried to do is change the y to 0, and factor the rest of the equation, but I keep getting left with a 4 that I can't seem to get rid of. My Algebra skills are a little rusty...please help.
0=4(4-x^2)
0=4(2+x)(2-x)
0=-2
0=2
(-2,0) and (2,0) are the x intercepts and the answers at the solutions part of the book, but why is that 4 still there?
This question is from textbook

Answer by Earlsdon(6294) (Show Source): You can put this solution on YOUR website!
Remeber the "zero product" rule?
If the either or or both.
Your work so far is immpecable. When you get to the line:
Apply the zero product rule:
Clearly not true.
thus
thus
You can ignore the 4 as it is not pertinent to the x-intercepts.
Another way to look at doing this problem (if the 4 still bothers you) is:
Divide both sides by -4.
Factor.
Apply the zero product rule.
or so...
or and these are the x-intercepts.

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