Determining Values for A, B, and C in Quadratic Formula

TiaharaJBennett said:
How did you get (4-4)?
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In order for the expression x - 4 to equal zero, there is only one number that x can possibly be. That number is 4.

4 - 4 = 0

If you're not convinced, then try subtracting 4 from other numbers, and try to get zero! Won't happen.


I probably gave you too much information to digest. Here's a summary.

mmm4444bot said:
What are the solutions to the equation (x - 4)(3x + 7) = 0 ?

Let's assume, one by one, that either factor is zero.

[That is, let us] apply the Zero-Product Property and write:

x - 4 = 0

OR

3x + 7 = 0

The solutions to these two equations … will be the same as the solutions to the original equation.
Click to expand...

How do we solve the equation x - 4 = 0?

Add 4 to both sides. :cool:

PS: When I use words like "product" or "factor", do you understand the meaning of those words?
 
Factors are what we call things that are multiplied together.

(3)(9) = 27

In this equation, the lefthand side is "factored". The factors are 3 and 9.

(x - 4)(3x + 7) = 0

In this equation, the lefthand side is factored. The factors are the symbolic numbers (x - 4) and (3x + 7).

Whenever we see factors produce a zero product, we know that one (or both) of those factors must be zero.
 
TiaharaJBennett said:
(2x + 1)(x + 3) = 0
Click to expand...

The Zero-Product Property tells us that

x + 3 = 0

OR

2x + 1 = 0


Let's solve x + 3 = 0.

Subtract 3 from both sides

x = -3

There's one answer.


Let's solve 2x + 1 = 0

Subtract 1 from both sides then divide both sides by 2.

x = -1/2

There's the other answer.


Now, if you still believe that using the Quadratic Formula is an easier way to get

x = -3 or x = -1/2

then I must tell you that you are entitled to your opinion.

Cheers :cool:
 
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