\(M=\left(2x+3\right)\left(2a-3\right)\left(4a^2+9\right)-\left(a^2+5\right)\left(a^2-5\right)\)
\(=\left(4a^2-9\right)\left(4a^2+9\right)-a^2+25\)
\(=16a^4-81-a^2+25\)
\(=16a^4-a^2-56\)
M = ( 2a+3)(2x-3)(4a2+9) - (a2 + 5)(a2 - 5)
M =[ (2a)2 - 32 ][(2a2)+ 32 ] - [(a2)2 - 52 ]
M = (4a2)2 - (32)2 - a4 + 25
M = 16a4 - 81 - a4 +25
M = 15a4 - 56