25x²-16-3(5x-4)(x+6)
Developpement
25x²-16-3(5x-4)(x+6)=25x²-16-3(5x²+30x-4x-24)
=25x²-16-3(5x²-26x-24)
=25x²-16-15x²+78x+72
=10x²+78x+56
Factorisation
25x²-16-3(5x-4)(x+6)=(5x+4)(5x-4)-3(5x-4)(x+6)
=(5x-4)[(5x+4)-3(x+6)]
=(5x-4)(5x+4-3x-18)
=(5x-4)(2x-14)
=2(5x-4)(x-7)