Question

How do you factor by grouping `56x^3 - 24x^2 + 35x - 15`?

Answer 1

Try collecting `7x` between the first and third term and `-3` between the second and fourth to get:
`7x(8x^2+5)-3(8x^2+5)`
Now collect `(8x^2+5)`:
`(8x^2+5)(7x-3)`