2(x-3x的平方+1)-3(2x的平方-x-2)
=2x-6x^2+2-6x^2+3x+6
=5x-12x^2+8
3(2a-3b)-(3a-2b)+5(a+b)
=6a-9b-3a+2b+5a+5b
=8a-2b
mn+3(m的平方n)-4(mn-2m的平方n)
=mn+3m^2n-4mn+8m^2n
=11m^2n-3mn
2(x-3x的平方+1)-3(2x的平方-x-2)
=2x-6x^2+2-6x^2+3x+6
=5x-12x^2+8
3(2a-3b)-(3a-2b)+5(a+b)
=6a-9b-3a+2b+5a+5b
=8a-2b
mn+3(m的平方n)-4(mn-2m的平方n)
=mn+3m^2n-4mn+8m^2n
=11m^2n-3mn