Question

If 81 x ² − 8 = (9x + b) (9x – b) , then the value of b is​

Answer 1

Step-by-step explanation:

81 x ² − 8 = (9x + b) (9x – b)

$81 {x}^{2} - 8 = {(9x)}^{2} - {b}^{2}$

$81 {x}^{2} - 81 {x}^{2} - 8 = - {b}^{2}$

$- 8 = - {b}^{2}$

${b}^{2} = 8$

$b = \sqrt{8}$

$b = \sqrt{2 \times 2 \times 2}$

$b = 2 \sqrt{2}$