How do you factor by grouping #20c^2 - 17c - 10#?
Have you missed a leading
If you have, then we have a simple problem:
If the quadratic as given is correct, it does not really group. It only has irrational factors:
There is another way. I use the new AC Method (Google , Yahoo Search) to factor trinomials.
To find p' and q', compose factor pairs of 200. Proceed: (-4, 50)(-5, 40)(-8, 25). This last sum (25 - 8 = 17 = -b) . Then p' = 8 and q' = -25.
Check by developing.