How do you factor completely #3x^2 - 9x - 30#?

1 Answer
Apr 29, 2018

Divide the whole equation by 3 to simplify:

#3x^2-9x-30=x^2-3x-10#

Find factors of #10# : #1,2,5,10#):
#2# and #5# work to make #10# and #3#

Therefore,

#(x+2)(x-5)#

Do not forget to add the three back!

#3((x+2)(x-5))#

So you would multiply out the brackets first, then the result should be #x^2-3x-10#. Multiply all factors out with #3# and this should give you #3x^2-9x-30#