Answer:
4(b-1)²-9 = 4b²-8b-5
4(b-1)²-9 = (2b+1)(2b-5)
Step-by-step explanation:
4(b-1)²-9 = 4(b²-2b+1)-9 = 4b²-8b-5
another way:
4(b-1)²-9 = [2(b-1)]²-3² = (2b+1)(2b-5)
4(b-1)²-9
= 4[(b - 1)(b - 1)] - 9
= 4[b² - b - b + 1] - 9
= 4(b² - 2b + 1) - 9
Opening bracket
= 4b² - 8b + 4 - 9
= 4b² - 8b - 5
