函数f(x)=x2+mx+n,A{x|f(x)=x},B{x|f(x-1)>x+5},若A={3},求集合B?
问题描述：
函数f(x)=x2+mx+n,A{x|f(x)=x},B{x|f(x-1)>x+5},若A={3},求集合B?
答
A={3}f(x) =xx^2+mx+n =xx^2+(m-1)x + n =0consider(x-3)^2 =0x^2-6x+9 =0compare the coef. of x and constant, we getm-1 = -6 and n = 9m = -5 and n = 9=> f(x) = x^2-5x+9for Bf...