Solving Quadratics by Factoring

Professor Dave Explains
22 Sept 201709:37
EducationalLearning
32 Likes 10 Comments

TLDRThis video teaches techniques for factoring polynomials to solve quadratic equations. It starts by reviewing FOIL method for multiplying binomials, then explains reverse process of factoring trinomials into binomials whose factors multiply to the constant term and add to the linear term. Several examples show how to find correct binomial factors, set them equal to zero, and solve for roots. The technique works for many but not all polynomials. Comprehension questions at the end reinforce key concepts like checking answers, applicability of method, and extending concepts to more complex problems.

Takeaways
  • πŸ˜€ We can factor polynomials using the reverse FOIL method. Break down the trinomial into binomial factors that multiply to the constant and add to the coefficient of the linear term.
  • 😊 To factor a polynomial like x^2 + bx + c, find two numbers that multiply to c and add to b. Put those numbers in the binomial factors.
  • 🧐 When factoring polynomials with a negative constant, consider negative and positive factor pairs.
  • πŸ€“ Factoring polynomials allows us to find roots by setting each factor equal to zero.
  • πŸ€” Be systematic when trying different factor pairs for the constant term until you find the pair that works.
  • 😳 Factor binomials starting with x must keep the coefficients straight - don't mix up which term gets multiplied.
  • πŸ˜‰ Always check factored polynomials by multiplying out the binomials using FOIL.
  • 😎 Factoring reveals the zeros of a polynomial equation by creating linear factors.
  • 🀩 Quadratic equations can be solved by factoring and finding values that make each factor zero.
  • πŸ₯³ Factoring polynomials is a useful algebra technique with many applications like solving equations.
Q & A
  • What is the goal when solving a polynomial equation like AX^2 + BX + C = 0?

    -The goal is to find values for X that make the equation true, or in other words, values to plug in for X that make the polynomial expression equal to zero.

  • How does factoring a polynomial help with solving polynomial equations?

    -Factoring allows you to break the polynomial down into binomial factors. If you set the factored polynomial equal to zero, you just need to find values of X that make either binomial factor equal to zero, which will make the whole thing zero.

  • What does it mean when a term in a polynomial has no coefficient, like the X term?

    -When there is no numerical coefficient in front of a term, that means the coefficient is 1 by default. So a term with just X means there is a coefficient of 1 that is not written.

  • What does FOIL stand for and what does it allow you to do?

    -FOIL stands for 'First, Outer, Inner, Last.' It is a process to multiply two binomials together to get a polynomial. FOILing binomials gives you a polynomial expression.

  • When factoring a polynomial like x^2 + Bx + C, what do you need to find?

    -You need to find two numbers, M and N, that can go in the binomial factors, where M and N multiply to give C and add to give B. This allows you to work backwards from the polynomial to extract the original binomials.

  • Why does order matter when placing factors in binomials during factoring?

    -Order matters because one binomial gets multiplied by a coefficient while the other does not. So the factors have to be placed correctly to give the right term when multiplying out the binomials.

  • What do you do when there is a negative constant term while factoring?

    -When there is a negative constant term, you have to consider negative factors in your pairs that multiply to give that term. A product of two negatives is a positive, so negatives are possible.

  • How do you check an answer after factoring a polynomial?

    -After factoring, you can multiply out the binomial factors using FOIL to make sure it gives you the original polynomial expression. You can also plug the solutions back into the original equation to verify the solutions work.

  • Why does factoring work to solve some polynomials but not others?

    -Factoring works whenever you can break a polynomial down into linear binomial factors. But some polynomials have no linear factors, like polynomials with higher order terms. Those cannot be factored into binomials.

  • What are the key steps to factor a simple polynomial?

    -The key steps are: 1) List pairs of factors for the constant term, 2) Find the pair that adds/subtracts to match the x term coefficient, 3) Place the factors correctly into binomials, 4) Check by multiplying binomials back out.

Outlines
00:00
πŸ€“ Introduction to Factoring Polynomials

This paragraph introduces factoring polynomials using the reverse FOIL method. It explains that factoring a polynomial allows you to express it as the product of two binomials. This can then be used to find solutions when the polynomial is set equal to zero.

05:03
😎 Step-by-Step Examples of Factoring Polynomials

This paragraph provides three step-by-step examples of factoring polynomials using the reverse FOIL method. It shows how to factor trinomials in the form Ax^2 + Bx + C by determining pairs of factors that multiply to C and add to B. Adding or subtracting the factors gives the middle term when FOILed.

Mindmap
Keywords
πŸ’‘polynomial
A polynomial is an algebraic expression consisting of variables raised to positive integer powers and combined using addition/subtraction. In the video, polynomials refer specifically to quadratic polynomials, which have a maximum power of 2 on the variable x. Factoring and solving these quadratic polynomials is a key focus of the lesson.
πŸ’‘factor
To factor means to express a polynomial as the product of two or more simpler polynomial expressions. The video demonstrates techniques to factor quadratic trinomials into the product of two binomials. This factorization allows for easier solving of the polynomial when set equal to 0.
πŸ’‘FOIL
FOIL stands for 'First, Outer, Inner, Last' and refers to a technique for multiplying two binomial expressions. Understanding FOIL allows for factoring polynomials through a reverse process.
πŸ’‘solve
To solve a polynomial means to find the values of the variable that make the polynomial equal to 0. The video shows how factoring facilitates solving by breaking the polynomial down into simpler binomials that can be individually set to 0.
πŸ’‘term
A term of a polynomial refers to each individual part combined with addition/subtraction. For example, '3x^2', '5x', and '-2' are the three terms in the polynomial '3x^2 + 5x - 2'.
πŸ’‘coefficient
The numerical factor of a term is called its coefficient. For example, in '3x^2', the coefficient is 3. Understanding coefficients is key when factoring polynomials.
πŸ’‘trinomial
A trinomial is a polynomial with three terms, such as 'x^2 + 7x + 10'. Factoring trinomials into binomials is a focus of the lesson.
πŸ’‘binomial
A binomial is a two-term polynomial such as 'x + 2'. The video shows how trinomials can be factored into the product of two binomials.
πŸ’‘standard form
The standard form for a quadratic polynomial is 'Ax^2 + Bx + C = 0', where A, B and C are coefficients. Setting a factored polynomial equal to this standard form allows for solving by setting factors equal to 0.
πŸ’‘solution
The solutions to a polynomial equation are the values of x that make the equation true, i.e. equal to 0. By factoring and setting factors equal to 0, the video demonstrates techniques to find these solutions.
Highlights

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Mindfulness interventions in schools improved academic performance, social skills, classroom behavior and ability to focus among students.

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Researchers concluded mindfulness-based interventions show promise for treating a variety of psychological and physical health issues.

More high-quality, large-scale randomized controlled trials are needed to further demonstrate the effects of mindfulness training.

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