@phi
can you factor the top and the bottom (and please repost the fraction)
|dw:1391638819424:dw|
if you factor it you get -5x+6/-1
the bottom is a "difference of squares" a^2 - b^2 it factors into (a+b)(a-b)
of yeah ok I will do that
?/(x+1)(x-1) I have no Idea how to factor the top I tried it another question with that same equation either on the top or bottom
to factor a quadratic, look at the last number +6 the + means the factors will have the *same sign* (- means different signs) now list all pairs of numbers that when you multiply them give you 6: 1,6 2,3 (nice short list) next, look at the number in front of the x: -5 the - means the largest factor is - (+ would mean the largest factor is +) from the first step, we know both factors have the same sign... both will be - look at our list with both numbers assigned - and add them. Do any add up to -5 ? -1-6= -7 no -2 - 3= -5 yes. -2 and -3 are our guys. we write (x -2)(x-3)
ok so how would we graph this
You probably skipped that lesson... but math builds on the earlier stuff... if you don't learn each step you will get stuck
ok you now have \[ y = \frac{(x-2)(x-3)}{(x+1)(x-1)} \] the zeros (where y=0 and the curve crosses the x-axis) happens when either of the top terms is zero. what x values cause y to be 0?
uhm -1, 1, 2, and 3 right?
only when the top is 0
ok so then it is 2 and 3
ok, make a note: zeros at x=2 and x=3 can you find the horizontal asymptote ?
uhm idk what to do how would I reduce that fraction
you do the same thing we did on the other problem...or was that your twin working that problem ?
hahaha yeah I know but when I do that the x's should disapear right?
yes, we just get y = # (ratio of the coefficients of the highest order term)
ok but when we get rid of the x's the denominator becomes 0 because of 1-1
using only the high order terms you get \[ y = \frac{x^2}{x^2} = 1\\ y=1\]
oh yeah ok so the horizontal is 1?
yes y=1 next, what are the vertical asymptotes ? (where you divide by 0)
-5/0 right?
you have \[ y = \frac{(x-2)(x-3)}{(x-1)(x+1)} \] what x's cause a divide by 0 ?
bottom
yes, but specifically what x values ?
1 and -1
ok, so what we know is 1 horizontal asymptote y=1 2 vertical asymptotes x= -1 and x=1 2 zeros at x= 2 and x=3
can you plot those lines and/or points ?
it looks like this
now we need to fill in the curve.
yeah but how do we do that
First, we now the curve is near y=1 when x is big. Let's figure out where it is when x is a large negative number if we pick x= -100, and plug that into the equation what do we get for y ?
\[ y = \frac{-102 \cdot -103}{-101 \cdot -99} \] it will be about +1.05 (above the line y=1)
ok. what does that mean?
I am sorry I am being difficult I have a massive headache and cant be done with school till this is done
as you go more and more negative the curve gets closer to 1 (but never reaches it... |dw:1391641347940:dw|
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