Question 345368
8k^(2)-18k-81

In this problem (9)/(4)*-(9)/(2)=-81 and (9)/(4)-(9)/(2)=-18, so insert (9)/(4) as the right hand term of one factor and -(9)/(2) as the right-hand term of the other factor.
(k+(9)/(4))(k-(9)/(2))

Remove the fraction by multiplying the first term of the factor by the denominator of the second term.
(4k+9)(2k-9)