化简(每题4分,共20分)(1) 3x2+2x-5x2+3x (2) 4(m2+n)+2(n-2m2)(3) -3(2x2-xy)-(x2+xy-6) (4) -(6a3b+2b2)+(4a3b-8b2)(5)先化简,再求值:3x2y-[2x2y-(2xy-3x2y)]+3xy2,其中x=3,y=-
计算: (1) (2)
计算: (1)(+45)+(-92)+5+(-8) (2) (3)÷ (4)+︱6-10︱-
计算: (2+1)(22+1)(24+1)=(2-1)(2+1)(22+1)(24+1)=(22-1)(22+1)(24+1)=(24-1)(24+1)=(28-1). 根据上式的计算方法,请计算(3+1)(32+1)(34+1)…(332+1)-的值.
计算 (1) (2)
计算:.