Question

(3b - 1) (3b + 1) use direct method to evaluate ​

Answer 1

Step-by-step explanation:

3b(3b+1)-1(3b+1)

9b²+3b-3b-1

9b²-1

Answer 2

Answer:

$(3b - 1)(3b + 1) \\ = (3b) {}^{2} { - 1}^{2} \\ = 9b {}^{2} - 1$

$formula \\ \\ (a - b)(a + b) = a {}^{2} - b {}^{2}$