Svp aider moi je comprend rien

I= 15x²+(25x²+2*5x*4+4²)
=40x²+40x+16

J=12x-(25x²+2*5x*6+6²)
=12x-25x²-60x-36
=-25x²-48x-36

K=-75x²-(25x²-2²)
=-100x²+4

L= (4x²-2*4x*6+6²) -(2x²-2*2x*7+7²)
=16x²-48x+36-4x²+28x-49
=12x²-20x+85