Question

Factor 5c^4 - 5c^2 - 60

Answer 1

first factor out a 5. what do you have?

Answer 2

c^4 - c^2 - 12

Answer 3

right
c^4 - c^2 - 12=0
now we call c^2=x

could you factor
x^2-x-12=0
????
after we put x=c^2 back in, and see what we have.

Answer 4

Still confused

Answer 5

can you factor
x^2-x-12=0
???

Answer 6

yes

Answer 7

5(c^2 + 3)(c^2 - 4)

Answer 8

exactly :)

Answer 9

sorry I don't know why I put =0 above, ignore that bit :/

Answer 10

Thks for your help :D

Answer 11

welcome

Answer 12

Oh sorry again, we can factor this even more by noticing that the part on the right is difference of squares:\[a^2-b^2=(a-b)(a+b)\]so\[5(c^2 + 3)(c^2 - 4)=5(c^2 + 3)(c - 2)(c+2)\]now it's completely factored.