1、原式=-x^6-3x^6-6x³+6x²=-4x^6-6x³+6x²2、原式=(3/4)a^6x²/(3/5)ax²+(6/5)a³x^4/(3/5)ax²-0.9ax³/(3/5)ax²=(4/5)a^5+2a²x²-(3/2)x
x-y+1=0则y=x+1斜率是1垂直则斜率是负倒数所以所求直线斜率是-1过(2,1)y-1=-1*(x-2)x+y-3=0 5.9*6.25-5.9*4.25 =5.9*(6.25-4.25)=5.9*2=11.8