Question

If (8z − 9)(8z + 9) = az2 − b, what is the value of a?

Answer 1

Answer:  a = 64

Explanation:

We use the difference of squares rule to say

(m-n)(m+n) = m^2 - n^2

So in this particular case,

(8z-9)(8z+9) = (8z)^2-(9)^2 = 64z^2 - 81

We can see that the 64 matches with the 'a' of the expression az^2-81, which must mean a = 64

Side note: This means b = 81