Sagot :
f(x)=(x^2-9)-2(x-3)(x+2)
=x^2-9-2(x^2+2x-3x-6)
=x^-9-2(x^2-x-6)
=x^2-9-2x^2+4x+12
=x^2-2x^2+4x-9+12
=-x^2+4x+3
=x^2-9-2(x^2+2x-3x-6)
=x^-9-2(x^2-x-6)
=x^2-9-2x^2+4x+12
=x^2-2x^2+4x-9+12
=-x^2+4x+3
f(x)=(x^2-9)-2(x-3)(x+2)
=x^2-9-2(x^2+2x-3x-6)
=x^-9-2(x^2-x-6)
=x^2-9-2x^2+4x+12
=x^2-2x^2+4x-9+12
=-x^2+4x+3
=x^2-9-2(x^2+2x-3x-6)
=x^-9-2(x^2-x-6)
=x^2-9-2x^2+4x+12
=x^2-2x^2+4x-9+12
=-x^2+4x+3