解:(1)3x2+2x﹣5x2+3x =(3﹣5)x2+(2+3)x =﹣2x2+5x; (2)4(m2+n)+2(n﹣2m2) =4m2+4n+2n﹣4m2 =6n; (3)5ab2﹣[a2b+2(a2b﹣3ab2)] =5ab2﹣a2b﹣2(a2b﹣3ab2) =5ab2﹣a2b﹣2a2b+6ab2 =11ab2﹣3a2b; (4)3A﹣2B =3(x2﹣3x﹣6)﹣2(2x2﹣4x+6) =3x2﹣9x﹣18﹣4x2+8x﹣12 =﹣x2﹣x﹣30; 当x=﹣1时,原式=﹣(﹣1)2﹣(﹣1)﹣30=﹣1+1﹣30=﹣30; (5)∵|x+1|≥0,≥0, 且|x+1|+=0, ∴x+1=0,y﹣=0, 解得:x=﹣1,y=, 代入数值转换器得:[(﹣1)2+2×+1]÷2=. |