求帮忙求下列函数的间断点.急.y=1/((x+2)²)y=sinx/xy=(x²-1)/(x²-3x+2)f(x)=x-1(当x≤1)3-x(x＞1)谢谢了

Question

求帮忙求下列函数的间断点.急.
y=1/((x+2)²)
y=sinx/x
y=(x²-1)/(x²-3x+2)
f(x)=x-1(当x≤1) 3-x(x＞1)谢谢了

Answer 1

y=1/((x+2)²),间断点x= - 2
lim x->0 sinx/x=lim x->0 cosx (洛必达法则)
=1,没有间断点
y=(x²-1)/(x²-3x+2)
=(x+1)(x-1)/[(x-2)(x-1)]=(x-1)/(x-2),间断点x= 2
f(x)=x-1(当x≤1) 3-x(x＞1)间断点x=1