Question

If (8z-9)(8z+9)=az^2-b, what is the value of a ? the value of a is ______ .

Answer 1

Answer: a = 64

if (8z - 9) (8z + 9) = az^2 - b

Firstly, we need to expand the parentheses

`\begin{gathered} (8z-9)(8z+9)=az^2-\text{ b} \\ 8z\cdot8z\text{ + 8z}\cdot9-9\cdot8z\text{ - 9 }\cdot\text{ 9} \\ 64z^2\text{ + 72z - 72z - 81} \\ 64z^2\text{ - 81} \\ \text{ relating the above expression with az}^2\text{ - b} \\ 64z^2-b=az^2\text{ - b} \\ \text{Therefore, a = 64} \end{gathered}`