Simplify this.

4 (b-1) ²-9

Step-by-step explanation:

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

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)