3x二次方—【2x —(4x二次方—3x)]其中x=—3
问题描述：
3x二次方—【2x —(4x二次方—3x)]其中x=—3
答
3x^2-[2x-(4x^2-3x)]
=3x^2-[2x-4x^2+3x]
=3x^2-2x+4x^2-3x
=7x^2-5x
当x=-3时，原式=7x^2-5x=7*(-3)^2-5*(-3)=63+15=78
答
原式=3x²-2x+(4x²-3x)
=3x²-2x+4x²-3x
=7x²-5x
=7×(-3)²-5×(-3)
=63+15
=78