Factoring 28s^2 + 8st - 20t^2: A Simplified Explanation and Solution

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In summary, the given expression is factored as 4(7s - 5t)(s + t) and the solution involves combining terms and recognizing a common factor. The individual attempting the solution initially struggled but eventually found the solution with the help of others.
  • #1
Rowah
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Homework Statement



[tex]28s^2 + 8st - 20t^2[/tex]

The answer in the back of the book is 4(7s - 5t)(s + t)

2. The attempt at a solution

[tex]4(7s^2 + st + st - 5t^2)[/tex]
[tex]4(7s^2 + st + st - 20t^2)[/tex]
[tex]4(s(7s + t) + t(s - 20t))[/tex]

I'm lost, can someone please help me?

Thanks in advance.
 
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  • #2
In your first attempt at the solution, why not combine the second and third terms inside the (), it might make things more obvious.
 
  • #3
Is there some trick to this that I am missing?

[tex]4(7s^2 + 2st - 5t^2)[/tex]
 
  • #4
Well, you could note that 2st=7st-5st, which makes your expression 4(7s2+7st-5st-5t2). Is this any easier to factorise?
 
  • #5
OHH OHH OHHHH OHHHHHH!

Oh my god, how could I be so blind? That t^2 at the end threw me off. I feel like such an idiot. Thanks a billion cristo and robb, and I apologize for wasting your time :)
 

1. What is a simple factoring problem?

A simple factoring problem is a mathematical equation in which you are asked to find two or more numbers that, when multiplied together, equal a given number. For example, the factoring problem 12 = 3 x 4 would have the solution of 3 and 4, as they are the factors of 12.

2. What is the purpose of factoring in mathematics?

The purpose of factoring in mathematics is to simplify complex equations and make them easier to solve. By breaking down a larger number into its smaller factors, we can find solutions or patterns that may not be immediately obvious with the original equation.

3. How do I know when I should use factoring to solve a problem?

Factoring is most commonly used when dealing with quadratic equations, but it can also be useful in simplifying fractions and solving polynomial equations. If you encounter a problem that involves finding factors or simplifying an equation, factoring may be a useful strategy to try.

4. What are some common techniques for factoring?

There are several techniques for factoring, including the difference of squares, grouping, and trial and error. These techniques involve looking for patterns, common factors, and using algebraic manipulation to simplify the equation and find the factors.

5. Are there any tips for factoring more efficiently?

One tip for factoring more efficiently is to start by looking for common factors, such as 2 or 3, before moving on to more complex techniques. It can also be helpful to use a factor tree or list out all of the factors of a number to see if any patterns emerge. Additionally, having a strong understanding of basic algebra and number properties can make factoring easier and faster.

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