1. a² –81 = (a +___)(a –___)
2. p² – q² = (____+___)
3. c²–d² = (c+d)(____+___)
4. 49e² –81f² = (e7 + ____)(___–9f)
5. 100g² – 121h² = (____+11h(10g –___)​