Step-by-step explanation:
For the first one, factor using difference of squares.
g² − 64h⁶ = (g − 8h³) (g + 8h³)
For the second one, factor out the greatest common factor, then factor the difference of squares.
k⁴ − 25k² = k² (k² − 25) = k² (k − 5) (k + 5)
For the third one, factor using AC method.
5×-18 = -90.
Factors of -90 that add up to +9 are -6 and +15.
Divide by 5 and reduce: -6/5, 15/5 = 3/1.
5r² + 9r − 18 = (5r − 6) (r + 3)
