I'm not good at quadratics at all, especially factoring simple problems...

ex. factor 8k^{2 }- 6k - 5

My attempt:

ax^{2}+ bx + c = 0

ac = -40 b = -6

find two numbers that the product is -40 and sum is -6

+4 and -10

8k^{2}+ 4k - 10k - 5

group like terms and then factor: This is the step I do not know how to do...

The answer is (4k - 5)(2k - 1)

Also, I have know clue where to start on this one:

0.4m^{2}+ 0.6m -1.8