计算：（1）3a(5a-2b) (2) (x-3y) (-6x)

计算：
(1)3a(5a-2b)
=3a*5a-3a*2b
=15a²-6ab
(2) (x-3y) (-6x)
=-6x*x+6x*3y
=-6x²+18xy
化简：
x(x-1)+2x(x+1)-3x(2x-5).
=x*x-x+2x*x+2x-3x*2x+3x*5
=x²-x+2x²+2x-6x²+15x
=x²+2x²-6x²-x+2x+15x
=-3x²+16x
计算：
(1)(2x+1)(x+3)
=2x*x+2x*3+x+3
=2x²+6x+x+3
=2x²+7x+3
(2)(m+2n)(m-3n)
=m*m-m*3n+2n*m-2n*3n
=m²-3mn+2mn-2n²
=m²-mn-2n²
(3)(a-1)(a-1)
=a*a-a-a+1
=a²-a-a+1
=a²-2a+1
(4)(a+3b)(a-3b)
=a*a-a*3b+3b*a-3b*3b
=a²-3ab+3ab-9b²
=a²-9b²
(5)(2x²-1)(x-4)
=2x²*x-2x²*4-x+4
=2x³-8x²-x+4
(6)(x²+3)(2x-5)
=x²*2x-x²*5+3*2x-3*5
=2x³-5x²+6x-15
耶耶耶耶耶…太辛苦了…可是不保证对…我看了下好像还有道题跟楼上不一样

计算：（1）3a(5a-2b)
=15a ²-6ab.
(2) (x-3y) (-6x)
=-6x ²+18xy.
化简：x(x-1)+2x(x+1)-3x(2x-5).
=x² -x+2x² +2x-6x² +15x
=x² +2x² -6x² -x+2x+15x...