Week 18- Top 5 Things I Learned In Pre-Calc 11

These are the top 5 things I learned this year in pre-calculus 11.
5: CDPEU
CDPEU (Can divers pee easily underwater) is a strategy I learned to easily factor equations.
C- Common (are there any common factors?). If yes, then take out the common factors.


D- Diffrence of squares (is there a difference of squares?). If yes, then you could easily factor.


P- Pattern (does it follow the pattern of x^2+x+a?). If yes then you could factor.


U- Ugly (Is it an ugly equation or can it be easily factored?), is there a coefficient in front or no? If yes then you will need a strategy, like the box method.


CDPEU is very useful and easy to remember, it will definitely help me in pre-calculus and calculus 12.
4: The Box Method
When you have reached the U part of CDPEU and you’ve determined that the quadratic equation you have is difficult to factor, the box method comes in handy.
Step one: Take the 1st term and place in the top left section of the box, place the 3rd term in the bottom right.


Step two: Multiply the two terms. Then, find two terms of the resulting product, which add up to the 2nd term.


Step three: Insert the two terms you just got into the box, the order doesn’t matter. Then find the greatest common factor of each row and each column.


Step four: combine the terms on the right into a binomial, then the terms on the bottom; you have your answer.


3: The Discriminant
The discriminant is the b^2-4ac portion of the quadratic formula. The discriminant is useful for determining the amount of solutions your quadratic equation has. You simply plug in the numbers from your quadratic equation into the discriminant and depending on the answer, you will know how many roots there are. If your answer is positive: there are 2 solutions, if the answer is 0: there is 1 solution, and if the answer is negative: there are no solutions. The discriminant is very useful, prior to solving the quadratic equation it’s always good to check the discriminant, if it’s negative, you already have your answer: there are no roots.

Step one: Identify abc values, and insert them into equation

Step two: Solve and identify how many roots there are based on the answer

2: Identifying Characteristics of a Parabola From an Equation 

When you are given a quadratic equation and are asked to graph it, it is important to know what each part of an equation means.

General Form: The General Form quadratic equation is one of the most common. The General Form equation tells you many things about a parabola. If term a of the equation is negative, you know that the equation opens down. Term c is always the Y-intercept. If there is no term c, that means the parabolas y-int is 0. If there is a middle term, that means that the parabola has moved somewhere along the a-axis (its x-int is not 0).

Standard Form: The Standard Form reveals the most important thing for graphing a quadratic equation: the vertex. P tells you the x value of the vertex, while q tells you the y value. But, when you take the p value to form the vertex, it’s sign always changes (if p was positive in the brackets, the vertex value is negative). The a value also tells you if the parabola stretches or compresses, if the a value is a>1, the parabola stretches, if 0<a<1, then the parabola compresses.

1: Changing from General Form to Standard Form

You cannot find the vertex of a parabola, just by looking at the General Form equation. So if you need to graph a parabola you must change the General Form into Standard Form. We can do this by completing the square.

Step one: Take half of the middle term, and square it. Then add the squared number to the first two terms, and subtract the squared number from the last term.

Step two: Factor what you have, and simplify. We know the vertex is at (-4,-4)

Week 17- Chapter 6: Trigonometry

The focus of this week is Trigonometry.

Important terms:

Initial Arm: The arm of an angle that lies on the x-axis.

Standard position: When the initial arm is on the positive x-axis.

Terminal arm: The terminal arm is the other arm, it can be anywhere and it determines  the angle.

Refrence angle: The closest angle between the Terminal arm and the x-axis.

Coterminal: Standard angle that shares the same terminal arm as another angle.

Rotation Angle: The angle from the initial arm to the terminal arm.

Ex: 

Sine Law:

The sine law can be used to find an angle or length of a side. To find the length of a side use the top formula, to find an angle, use the bottom formula (the reciprocal). You can only use the sine law if you have both the angle and side of one of the fractions, such as angle A and side a, or angle B and side b, etc.

Cosine Law:

The cosine law can be used instead of the sine law, if there are no fractions that have a value for both the angle and the length of the side.

You can tell if you need to use sine law or cosine Law just by looking at a triangle. If there is an angle in the triangle with a side value across from it, you can use sine law. But, if the angles don’t have a side measurement across from them, you will have to use cosine law.

In this example, you can use sine law:

In this example, you have to use cosine law:

The CAST rule:

The cast rule is an easy way to remember, which trigometric ratios are positive and which are negative in every quadrant.

Updated SOH CAH TOA:

In this unit SOH CAH TOA is updated to SYR CXR and TYX. When given a (x,y) point on the terminal arm, we can determine the refrence angle using the updated SOH CAH TOA.

Week 16- Problem Solving Rational Expressions Involving Proportions

How to solve problems involving proportions:

How much lemon juice should be added to 9L water to make a lemonade that is 30% lemon juice?

Step one: Make an equation by reading the question and identifying the components of the equation.

Step two: Simplify the equation by cross-multiplying and moving all the X’s to one side.

Step three: Solve the equation by isolating the X. The answer is 27/7 Litres.

Week 15- Adding and Subtracting Rational Expressions

When adding or subtracting Rational Expressions, the denominator always has to be the same for all Expressions.

Step one: Make sure the denominator is the same by factoring both denominators and then multiplying the factors. If the two denominators have same factors, they cancel out. After you find the common denominator, you can combine the Fractions into one big fraction.

Step two: What you do to the bottom, you have to do to the top. We have to look at what could multiply 6x into 18xy, it would have to be 3y. So we multiply the numerator by 3y. Then we have to look at what multiplies 9y into 18xy, it would have to be 2x, so we multiply the numerator by 2x.

Step three: once the denominators are the same, and the numerator has been multiplied, we can combine the fractions into one big fraction, and simplify.

 

Week 13: Graphing Linead Reciprocal Functions

This week I learned about graphing reciprocal functions.

Step 1: Graph the linear function:

Step 2: Identify the asymptotes by first identifying the invariant points (the invariant points are always at the 1 and -1 y-axis points on the linear function, the asymptote goes directly through the middle of the invariant points, the other asymptote is always on the x-axis).

Step 3: Graph the hyperbolas:

Week 12: Solving Quadratic Systems of Equations

This week I learned about solving quadratic systems of equations.

A linear-quadratic system can have 3 possible solutions:

1) 2 solutions (line intersects parabola at 2 points)

2) 1 solution (Line intersects parabola at 1 point)

3) 0 solutions (line doesn’t intersect parabola)

A quadratic-quadratic system could have 4 possible solutions:

1) 2 solutions (parabolas intersect at 2 points)

2) 1 solution (parabolas intersect at 1 point)

3) 0 solutions (parabolas don’t intersect)

4) infinite solutions (parabolas are on top of one another)

How to solve a quadratic-quadratic system graphically:

Step one: Identify clues from the equations

Step two: graph the equations

Step three: Identify the intersects

The parabolas have 2 solutions (-2,-2) and (2,-2)

Week 11- Solving Quadratic Inequalities

This week in math I learned about solving quadratic inequalities.

When solving quadratic inequalities, you always have to remember that if you are dividing by a negative, you have to flip the inequality sign.

Step 1: Find the roots of a quadratic inequality:

Step 2: Insert the roots into a numbe line:

Then you can pick 3 numbers from the 3 sections on the number line and insert them into the original equation.

I picked 0 becuase it is quick and easy:

I got a positive number so, any number below 2 is positive.

Then I did the same with the number 3:

I got a negative number, that means that all numbers between 2 and 7 would result in a negative number.

Then I did the same with 10 and got a positive number, which means all numbers above 7 would result in a positive number. But the equation is asking which number could be inserted into the equation that would result in negative number. Looking back at the number line I see that all numbers beteeen 2 and 7 would result in a negative number. So the answer is 2<x<7.

Week 10- Sequences and Series Review

The unit I needed to recall the most was the Sequences and Series unit. Specifically Infinite Geometric Series. These are the types of infinite geometric series:

Diverging series expand each time so its impossible to determine a sum because the numbers grow so much each time they are multipled by the common ratio. In a diverging series the common ratio has to be negative.

Unlike diverging series, converging series do have a sum, converging series converge, and eventually the numbers will be so small that you could determine a sum. The ratio for a converging series needs to be bigger than -1 and smaller than 0.

This is the formula for finding the sum of a converging series .

 

Week 9- Equivalent Forms of the Quadratic Function

The General Form and Standard Form can be converted to Equivalent Forms. This can be useful if you are trying to find the vertex or y-intercept.

To convert from General Form to Standard Form we complete the square:

Now we know that the vertex is at (-3, -3)

To convert from Standard Form to General Form we expand the equation:

Now we know that the y-intercept is at 15.