谁来帮我做一下几个一元一次方程的题啊啊、、(1) 2（3xy-2x²-3y²)+3(x²-5xy+3y²)(2) 3(x²-2x+1)-4(2x²-x-3)(3) -(-a²+2ab+5²)+(-a²-ab+b²）,其中a=1/30,b=20
问题描述：
谁来帮我做一下几个一元一次方程的题啊啊、、
(1) 2（3xy-2x²-3y²)+3(x²-5xy+3y²)
(2) 3(x²-2x+1)-4(2x²-x-3)
(3) -(-a²+2ab+5²)+(-a²-ab+b²）,其中a=1/30,b=20
答
-x2-9xy+3y2
-5x2-2x+12
377
答
(1) 2（3xy-2x²-3y²)+3(x²-5xy+3y²)
=6xy-4x²-6y²+3x²-15xy+9y²
=-x²-9xy+3y²
(2) 3(x²-2x+1)-4(2x²-x-3)
=3x²-6x+3-8x²+4x+12
=-5x²-2x+15
(3) -(-a²+2ab+5b²)+(-a²-ab+b²）
=a²-2ab-5b²-a²-ab+b²
=-3ab-4b²
=-3×1/30×20-4×20²
=-2-1600
=-1602
答
(1) 2（3xy-2x²-3y²)+3(x²-5xy+3y²)= 6xy-4x²-6y²+3x²-15xy+9y²= 6xy-15xy-4x²+3x²+9y²-6y²=-9xy-x²+3y²(2) 3(x²-2x+1)-4(2x²-x-...