Explanation:
step 1. if k is a zero then (x - 1) is a factor of 4x^3 + 23x^2 - 34x + 7.
step 2. we "can" use long division but synthetic division is easier!
step 3. 1 4 23 -34 7
4. 4. 27. -7.
4 27. -7. 0 (must get 0)
step 4. so the factors are (x - 1)(4x^2 + 27x - 7).
step 5. please note if you multiply these factors together you will get the original polynomial!