(1)2（a^2-ab)-2a^2+3ab (2)5(2x-7y)-3(4x-10y) (3)(x+y)-[3x+(-x+y)]

(2a²-ab+1)-2(a-2ab+3) 计算：a^2×(-a)^2×(-a)^3（-ab）^2·（2a^2-ab-1) 计算(a^3-4a^2b-a+4ab^2)/a(a-2b+1) 已知a+b=A,ab=A+2008,1-2（a+ab）+（ab-2b）=3A.求a+b和ab的值 已知a+b=A ab=A+2008 1-2(a+ab)+(ab-2b)=3A 求a+b ab的值 已知a+b=A ab=A+2008 1-2(a+ab)+(ab-2b)=3A 求a+b ab的值 因式分解：a×a×a-2a×a×b+ab×b 3(-ab+2a)-(3a-b) 3(-ab+2a)-(3a-b) (a-b)^3+2ab(a-b) a^3-ab^2 =a （a^2 -b^2) =a(a+b)(a-b) (a-b+ab-a^2/a+b)乘以[a+1/a-b乘以(1+a/b)] a(a-1)-(a×a-b)=-5,求(a×a+b×b)÷2-ab (5a-3a^2+1)-(4a^3-3a^2)-2(ab-3a^2)-[2b^2-(5ab+a^2)+2ab] 若a-b等于4,ab等于1,求（-2ab+2a+3a)-(3ab+2b-2a)-(a+4b+ab)的值 a-ab^2因式分解 a+b/2ab 2AB/A+B