SOLUTION: This problem is on my study guide for my final tomorrow (06/28/11)! Please help! I'm not sure if this even falls under just "Equations." x²-16 over x²+6x+8 and x²-3x-10 over x

Algebra ->  Equations -> SOLUTION: This problem is on my study guide for my final tomorrow (06/28/11)! Please help! I'm not sure if this even falls under just "Equations." x²-16 over x²+6x+8 and x²-3x-10 over x      Log On


   



Question 464931: This problem is on my study guide for my final tomorrow (06/28/11)! Please help! I'm not sure if this even falls under just "Equations."
x²-16 over x²+6x+8
and x²-3x-10 over x²-25


Found 2 solutions by josmiceli, ewatrrr:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
+%28x%5E2+-+16%29+%2F+%28x%5E2+%2B+6x+%2B+8%29+
Anything that looks like this, usually you
must factor the top, bottom, or both.
Here you must factor both top and bottom
--------------------------------
The top is the difference of 2 squares, and the factors
always look like +%28x+%2B+4%29%2A%28x+-4%29+ because the
middle term gets subtracted out like this:
+%28x+%2B+4%29%2A%28x+-+4%29+=+x%5E2+%2B+4x+-+4x+-+16+
---------------------------------
A good way to factor the bottom is to " complete
the square"
First set the expression equal to zero,
Then subtract 8 from both sides
Take 1/2 the coefficient of x, square it, and
add it to both sides
+x%5E2+%2B+6x++%2B+%286%2F2%29%5E2+=+-8+%2B+%286%2F2%29%5E2+
+x%5E2+%2B+6x+%2B+9+=+-8+%2B+9+
+%28x+%2B+3%29%5E2+=+1+
Take the square root of both sides
+x+%2B+3+=+1+
+x+%2B+2+=+0+
and
+x+%2B+3+=+-1+
+x+%2B+4+=+0+
The factors are +x+%2B+2+ and +x+%2B+4+
Now the original fraction looks like:
+%28%28x+%2B+4%29%2A%28x+-+4%29%29+%2F+%28%28x+%2B+2%29%2A%28x+%2B+4%29%29+
This is the same as:

-------------------------------------
The 2nd problem has the difference of 2 squares on the bottom
You can factor the top just as in the 1st problem.
The bottom is: +x%5E2+-+25+=+%28x%2B5%29%2A%28x-5%29+
When you complete the squares, the top is:
++x%5E2+-+3x+-+10+=+%28x+-+5%29%2A%28x+%2B+2%29+
Now you have:

Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 
Hi,
factoring numerator and denominator:
x^2 - 16 = (x-4)(x+4)
x^2 + 6x + 8 = (x+2)(x+4)

x^2 - 3x + 10 = (x-5)(x+2)
x^2 - 25 = (x-5)(x+5)
%28cross%28x-5%29%29%28x%2B2%29%2F%28cross%28x-5%29%29%28x%2B5%29=+%28x%2B2%29%2F%28x%2B5%29