MATH 536 CHEAT SHEET INFO

To find f [ g(x) ] first replace g(x) with its expression and then apply f to it.

Example

 f (x) = x 2 + 3x – 2 g (x) = 1 – x f [ g(x) ] = f ( 1 – x ) = ( 1 – x ) 2 + 3(1 – x) – 2

f (x) = a | x – h | + k vertex at (h, k) a > 0 up a < 0 down
** a is the slope of one branch and a is the slope of the other branch.
To find the rule not given the vertex, find the equations of the 2 branches,
the vertex is their point of intersection.

Basic Rule of Inequalities:

when dividing or multiplying by a negative, change the direction of the inequality.

| f (x)| < a becomes – a < f (x) < a (mitten thumbs in)
| f (x) | > a becomes f (x) < a and f (x) > a (mitten thumbs out)
** Isolate the absolute value expression before setting up the intervals.

 vertex at (h, k) a > 0 up a < 0 down b = +1 right b = – 1 left

ex: becomes

so vertex is at (– 3, 7) curve moves up and left from vertex.

.

Same basic rule of inequalities.

ex: u 9(x + 1) < (2x + 3)² u 9x + 9 < 4x² – 12x + 9.

NOTE: we're squaring SIDES of the equation if the side is a binomial we get a trinomial!

so we're solving the quadratic inequality 4x 2 – 21x > 0, which means x(4x – 21) > 0
Since this is a parabola opening upwards with zeros at 0 and 21/4
the positive y-values on the curve are found left of 0 and right of 21/4. (thumbs out)
The solution set is x > 21/4 and –1 < x < 0, since the restriction on is x

We must always check our solutions in square root equations and inequalities.
They don't all work! We have to respect the restrictions on the radical expression.

Hint: To find the rule for a square root function, if given the vertex and another point,
decide if the curve moves left or right so you know if b is +1 or – 1.
Then include it in the rule of correspondence.

.

f (x) = a [ b(x h) ] + k
note : [ a ] means greatest integer of a.

 if a > 0 & b > 0 steps up if a < 0 & b > 0 steps down if a > 0 & b < 0 steps up if a > 0 & b < 0 steps down b > 0 open on right b < 0 open on left for steps up open on the left, make a < 0 & b < 0 vertical separation of steps = | a | horizontal length of steps = domain: R depends on reality (could be R > 0) start at (h, k) range: an + k, n Z (or strictly positive or negative)

note: left of 0, be careful. ex [ – 9.2] = – 10

.

 general form: standard form: Intercepts decide increasing or decreasing: x-intercept: , y-intercept: , if a < 0 the curve is always increasingif a > 0 the curve is always decreasing vertical asymptote (x that makes denominator = 0)general form: , standard form: x = h horizontal asymptote (ratio of the coefficients of x)general form: standard form: y = k,

note: asymptotes are LINES so we write an equation not a constant!!!

With the general form of the rule, we find the intercepts (set x = 0 and y = 0) so we can tell if the curve increases or decreases over its domain.

.

Example: we'll sketch the graph of

 Vertical Asymp : x = – 1 Horizontal Asymp: y = 4 y-int = – 8 (set x = 0) zero = 2 (set y the numerator = 0) Dom: R; x ! – 1 Rng: R; y ! 4 always increasing f (x) is negative ] – 1, 2 ] f (x) is positive ] – º, – 1 [ 4 [ 2, º [

.

.

.

Since an even # of negatives multiplied or divided make a positive,
and an odd # of negatives multiplied or divided make a negative,
once we establish the zeros of the fraction's factors,
we test each interval created for the result we need -- positive or negative.

Example:

solve

the zeros of the factors are x = – 2 and x = 5 we set up a number line like this

______ 2__________ 5 ____

which creates 3 intervals -- left of – 2, between – 2 and 5, and right of 5.

set x = – 3 the fraction is positive ( > 0)

set x = 0 , the fraction is negative (< 0)
set x = 6 the fraction is positive ( > 0)

The solution is x – 2 and x > 5

If equality is included, the solution only includes the zero of the numerator since the denominator can't be equal to 0. Division by zero is still undefined.

f(x) = a(c) b ( x – h ) + k raise C b for the new base to eliminate the b.

Example: f (x) = – 5 (3) 2 ( x – 5 ) + 7 becomes f (x) = – 5( 9) ( x – 5 ) + 7 use 3 2 or 9 as c.

Example: list the properties of f (x) = – 5(½) 2 ( x + 3 ) – 1; [(½) – 2 = 4]

the function becomes f (x) = – 5(4) – 2 ( x + 3 ) – 1

analysis: base > 1, a < 0 so curve is always decreasing
HA: y = – 1, y-int = – 321

 Dom: R Rng: ] , – 1 [ no zero always decreasing.
.

Example: find an equivalent expression for

log a 1 + log a a 2 + log a (a/2)

0 + 2 + log a a – log a 2 = 3 – log a 2.

Example: solve log 5 (x - 1) + log 5 (x + 3) – 1 = 0 becomes log 5 (x 2 + 2x – 3) = 1

now go to exponential form, solve the quadratic x 2 + 2x – 3 = 5

Example: find the numerical value of 2 log b 1 + log b b 2 + log b (1/b)

2(0) + 2 + log b 1 – log b b = 2(0) + 2 + 0 – 1 = 1

graph the inequalities, solve for the vertices,
find the max. or min. for the target objective.

Note: watch for situations where only integer or positive coordinates suit the reality of the situation. We can't rent ½ a bus or hire ½ a person. We can't have negative time values.

switch the x's and y's, then solve for y.

When we find an inverse function, we switch the domain and range, so restrictions on the domain and range of f (x), determine restrictions on f – 1(x). The domain and range restrictions are reversed.

Example: find f – 1(x) if f (x) = , x – 5 and y ¼

= f – 1(x) so y – 5 and x ¼.

Example: find f – 1(x) if f (x) = 2, we get x = 2

so y = and since x 1 in f (x), y 1 in f – 1(x).

.

Euclidean Geometry of the Circle and Right Triangle:

these lessons are in the Geometry MathRoom logID: plgm4, plgm5 and plgm6

see pg. 322 in Book 1 for the list of theorems.

Statistics:

mean deviation: where xi are the data values, is the mean, n = # of data items

standard deviation: for a sample; for a population.

Z-Score or Standard score: measures the # of standard deviations between

the data value and the mean of the distribution.
for a sample; for a population
If z is negative, the data value is below the mean.
If z is positive, the data value is above the mean.

Bivariate Stats:(2 variables)

Scatter Plots, Correlation, and Line of Regression:

To get the "a" and "b" for the line of regression y = ax + b , enter the 2 lists of data values, then use 2-var stats and linreg from the Stats menu on your calculator. If asked to find the value for a different data value, plug this x-value into the equation for the line.

To find the correlation coefficient r, use either the formula for the rectangle or use your calculator. Strong correlation comes from values of r close to .

.

Know your identities (on your bookmark), the unit circle, the two triangles, the restraints on the sine, cosine and tangent functions, and the definitions of the six trig functions.

 standard forms for the equation of a circle with center (0, 0), radius = r with center (h, k), radius = r equation is x 2 + y 2 = r 2 . equation is (x – h) 2 + (y – k) 2 = r 2 .

To get to standard form from general form x 2 + y 2 - 2hx - 2ky + c = 0 ,
take ½ of the coefficients of x and y to find (h, k), then set c = h 2 + k 2 – r 2 to solve for r.

since the tangent is perpendicular to the radius at the point of contact, find the slope of the radius, take the negative reciprocal to get the slope of the tangent.
Write the equation of the tangent line using the slope and the point of contact.

.

Ellipses: The sum of the distances from a point on the ellipse to the foci = 2a.

 standard forms for the equation of an ellipse center (0, 0) center (h, k) a is the semi-MAJOR axis b is the semi-minor axis c = focal distance (between center and a focus), c 2 = a 2 – b 2 .

With the ellipse, the larger of a 2 and b 2 always goes under the variable of the major axis.
So, if the ellipse is vertical, the larger value goes under the y term.

latus rectum: is the chord of the ellipse, perpendicular to the major axis through the focus.

To find its length, find c and set x (or y) = c for the corresponding values of the other variable. Then find the length.

.

Hyperbolae: The difference between the distances from a point on the hyperbola to the two foci is constant and is equal to 2a.

Hyperbola Equations:

 center (0, 0): center (h, k):

where a is always horizontal and b is always vertical.
If the hyperbola is vertical, use – 1.

The axis through the vertices is the transverse axis.
The axis perpendicular to it is the conjugate axis.

The foci are always on the transverse axis,
the focal distance is the distance between the center and the focus.

asymptotes: The equations of the asymptotes to the hyperbola are:

Parabolas: every point on the path is equidistant from the focus and the directrix.

c is the focal distance -- the distance between the focus and the vertex,
or the distance between the vertex and the directrix.

 opening up or down opening left or right (x – h) 2 = ! 4c (y – k) (y – k) 2 = ! 4c (x – h)

TEXT BOOK STUDY GUIDE: (Carousel/Mathematical Reflections Series)

Book 1:

Workout #1 pgs 145 - 159 covers 1st 4 functions (abs. val, sq. rt., step, rational)
Workout #3 pgs 226 - 236 covers optimization.
Workout #4 pgs 324 - 334 covers Euclidean Geometry
Workout #5 pgs 372 - 387 covers exponential function
Workout #6 pgs 416 - 424 covers logs.

Book 2:

Workout #8 pgs 104 - 115 covers statistics
Workout #10 pgs 297 - 310 covers trig
Workout #11 pgs 376 - 389 covers conics.