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algebra 2

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11,300 possible mastery points

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The Algebra 2 course, often taught in the 11th grade, covers Polynomials; Complex Numbers; Rational Exponents; Exponential and Logarithmic Functions; Trigonometric Functions; Transformations of Functions; Rational Functions; and continuing the work with Equations and Modeling from previous grades. Khan Academy's Algebra 2 course is built to deliver a comprehensive, illuminating, engaging, and Common Core aligned experience!

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Wolfram MathWorld: The Web's Most Extensive Mathematics Resource

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Algebra Applied Mathematics Calculus and Analysis Discrete Mathematics Foundations of Mathematics Geometry History and Terminology Number Theory Probability and Statistics Recreational Mathematics Topology

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A Puzzle

What is the missing number?

OK, the answer is 6, right? Because 6 − 2 = 4. Easy stuff.

Well, in Algebra we don't use blank boxes, we use a letter (usually an x or y, but any letter is fine). So we write:

It is really that simple. The letter (in this case an x) just means "we don't know this yet", and is often called the unknown or the variable.

And when we solve it we write:

Why Use a Letter?

Because:

it is easier to write "x" than drawing empty boxes (and easier to say "x" than "the empty box").

if there are several empty boxes (several "unknowns") we can use a different letter for each one.

So x is simply better than having an empty box. We aren't trying to make words with it!

And it doesn't have to be x, it could be y or w ... or any letter or symbol we like.

How to Solve

Algebra is just like a puzzle where we start with something like "x − 2 = 4" and we want to end up with something like "x = 6".

But instead of saying " obviously x=6", use this neat step-by-step approach:

Work out what to remove to get "x = ..."

Remove it by doing the opposite (adding is the opposite of subtracting)

Do that to both sides

Here is an example:

Solved!
Why did we add 2 to both sides?

To "keep the balance"...

In Balance

Add 2 to Left Side

Out of Balance!

Add 2 to Right Side Also

In Balance Again

Just remember this:

To keep the balance, what we do to one side of the "="
we should also do to the other side!

See this in action at the Algebra Balance Animation.
Another Puzzle
Solve this one:

What we want is an answer like "x = ...",
but the+5 is in the way of that!
We can cancel out the+5 with a −5 (because 5−5=0)

Have a Try Yourself

Now practice on this Simple Algebra Worksheet and then check your answers. Try to use the steps we have shown you here, rather than just guessing!

Try the questions below, then read Introduction to Algebra - Multiplication

1725,1726,1727,1728,3135,3136,3137,3138,3850,3851

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What is the missing number? OK, the answer is 6, right? Because 6 − 2 = 4. Easy stuff. Well, in Algebra we don't use blank boxes, we use a letter (usually an x or y, but any letter is fine). So we write: It is really that simple.

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11,200 possible mastery points

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Learn the basics of algebra-focused on common mathematical relationships, such as linear relationships.