Help me i do not understand this

that is 81 which is 9 ^2 and you can you use

Step-by-step explanation:

(a^2 -b^2)=(a-b)(a+b)

=(9^2-8^2)

=(9-8)(9+8)

step-by-step explanation:

the multiplicative inverse of a fraction a/b is b/a. for the multiplicative inverse of a real number, divide 1 by the number. for example, the reciprocal of 5 is one fifth 1/5 or 0.2, and the reciprocal of 0.25 is 1 divided by 0.25, or 4.