## week 15 precalc

this week we finished unit 7 on rational expressions.

In 7.4 we learned how to simplify rational expressions with binomials or trinomials.  first you must factor or simplify any functions in the expression before finding the lowest common denominator.  then by multiplying the numerator with the common denominator you can start to add the like terms of the expression together and make it into one whole fraction.

Ex :

$\frac {6}{v-2} + \frac {7}{2v+7}$

$\frac {12v+42}{(v-2)(2v+7)} + \frac {7v-14}{9v-2)(2v+7)}$

$\frac {19v+28}{(v-2)(2v+7)}$

v cannot equal 2 or $\frac {-7}{2}$

In 7.5 we solved rational equations by eliminating the fractions, bringing everything over to one side and either isolate or factor to find x.

Ex:

$\frac{4}{5x-2} = \frac {3}{4x-1}$

$16x-4=15x-6$

$x=-2$

$x= \frac{2}{5} , \frac {1}{4}$

In 7.6 we solved word problems involved with rational expressions.  With word problems involving time, speed and distance we would use the TSD triangle to help find and equation with variables to help find the average speed.  With problems involving work we need to create a chart that shows the fraction of work done in each period of time.  in these problems, the expression will always equal 1 because in a case of mowing a lawn, you are mowing 1 whole lawn not multiple lawns.

## week 14 precalc 11

This week we started with unit 7 of rational expressions.  We started with the basics of non-permissible values which are the values of x that make the denominator equal zero.  By simplifying rational expressions we can find x which are the non-permissible values.

In 7.2 we learned how to multiply and divide rational expressions by cross cancelling when simplified.

$\frac{3x}{2(x-3)} \frac{8(x-3)}{9x^2}$

$\frac{4}{3x}$

x cannot equal 3 and 0.

Then we learned how to add and subtract rational expressions with monomial denominators.  by finding the common denominator we can expand and reduce to end up with one simplified fraction.

$\frac{2x-3}{x} + \frac{x-1}{3x}$

$\frac{6x-9}{3x} + \frac{x-1}{3x}$

$\frac{7x-10}{3x}$

x cannot equal 0

## week 13 -Precalc11

This week we continued with unit 8 of reciprocal functions and graphing.  This is a new concept so it was a challenge to wrap my head around these new concepts and vocabulary.

In lesson 8.3 we learned the most in my opinion.  there were some new vocabulary with this unit to help us graph the function :

invariant points : points that don’t change.

hyperbola : the graph of a reciprocal function

horizontal asymptote : The y value that the parabola never touches

vertical asymptote : the x value that the parabola never touches.

the reciprocal of a function will always look like this :

$x+3$

into ->

$\frac{1}{x+3}$

It will always be a fraction under 1.

This new way of graphing was interesting which made it kind of fun to learn since it was different and we had to think about graphing in a new way.

In lesson 8.5 we did the same thing, but we now had to graph reciprocal QUADRATIC functions.  it’s similar to linear in the sense that their will be invariant points and asymptotes, but completely different in how we graph the parabolas.  sometimes there will be more then 2 invariant points like in $\frac{1}{x^2-4}$ there will be 4.  we have to be careful when drawing the asymptotes because there will now be 3 lines instead of 2.  like always $y=0$, but the x values will be 2 and -2.  By the end we will have 2 parabolas beside each other on quadrant 1 and 2, also a parabola facing down below in the middle.