Factor by Grouping.

Question

15r^2-19r+6

Answer 1

multiply 15 by 6 to get 90
Now find two numbers which when multiplied will give you +90, and when added will give you -19
I found -10 and -9
so replace the -19r with -10r - 9r
15r^2-19r+6
= 15r^2 - 10r - 9r + 6
Here is where the "grouping" comes in
= 5r(3r - 2) - 3(3r - 2)
= (3r - 2)(5r - 3)