Factor the polynomials completely, Please show a work! Problems entered in comments :)

Question

anonymous · Answer

1) $$5y^2-20$$
2) $$4s^2-1$$
3) $$3b^3-13b^2+10b$$

studygurl14 · Answer

Only one question per thread please. 
When factoring, always find the greatest common factor of each number. 
1) $5y^2-20$
What is the GCF of $5y^2$ and $20$?

anonymous · Answer

5.

anonymous · Answer

Just give steps to solve this type rather than this specific question please.

studygurl14 · Answer

Correct. Set it up like this:
$\large 5y^2-20\rightarrow 5(?+?)$
find what the question marks are by dividing $5y^2$ and $-20$ by 5.

studygurl14 · Answer

With these types of problems, always search for the GCF first.

anonymous · Answer

Okay, so the answer is (y^2+-4)?

studygurl14 · Answer

not quite. You have to leave the 5 there. so $\large 5(y^2-4)$

anonymous · Answer

Okay, great. Thank you!

studygurl14 · Answer

:)