Day 84 – January 11

Algebra: Chapter 5, Lesson 10, page 245.

Multiplying Binomials: Special Products

We can use the FOIL or BOX methods to multiply binomials. There are however, 3 special cases that if you recognize them, will save you some work:

  1. `(A+B)(A-B)=A^2−B^2`
  2. `(A+B)(A+B)=A^2+B^2+2AB`
  3. `(A−B)(A−B)=A^2+B^2−2AB`

Remember, that `A` and `B` are the terms (monomials or constants) that we just plug in. If you forget these 3 cases, that’s OK, just FOIL or BOX the binomials and the answers are still the same.

For example:

`(2x + 7)(2x – 7)` where `2x = a` and `7 = b`, we have an answer of `4x^2 – 49`.

Another example:

`(2x + 7)(2x +7)` where again `2x = a` and `7 = b`, we have an answer of `4x^2 + 49 + 2*2x*7` or `4x^2 +28x + 49`!

Go slow and you’ll be fine.

Two of tonight’s homework problems solved by MrE are here! Just click it!

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Algebra 1a: Chapter 4, Lesson 6, page 194.

Reasoning Strategies

Three steps to follow:

  1. UNDERSTAND the problem
  2. Develop and carry out a PLAN
  3. Find the ANSWER and CHECK

You can also these strategies:

  • Draw a diagram
  • Make an organized list
  • Look for a pattern
  • Try, test and revise
  • Use logical reasoning
  • Simplify the problem
  • Write an equation
  • Make a table
  • Work backward!
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