"f(x)g(x)=o f(x)=0或g(x)=0"对吗?

f(x)g(x)=o f(x)=0或g(x)=0对吗? 设f(x)=o,x0 g(x)=0,x0 求f[f(x)],g[g(x)],f{g(x)],g[f(x)] | f(x) | / | g(x) | = | f(x)/g(x) | 吗? 已知f(x)=x^2-1,g(x)=x-1(x小于0)或2-x(x大于0),求f[g(x)]与[f(x)] max{f(x),g(x)}=1/2(f(x)+g(x)+|f(x)-g(x)| 证明(f(x)*g(x))'=f'(x)*g(x)+g'(x)*f(x) 证明(f(x)*g(x)）'=f(x)'*g(x)+g(x)'*f(x) f[g(x)]=f(x)*g(x)? 函数f(x)为奇函数,g(x)为偶函数,且f(x)-g(x)=x-x^2,求f(x)+g(x)的最大值或最小值 关于函数无穷大无穷小的阶的问题Interpret and prove3 the following relations as x → x0 ∈ R:O(f(x)) + O(g(x)) = O(|f(x)| + |g(x)|),O(f(x))o(g(x)) = o(f(x))o(g(x)) = o(f(x)g(x)),o(O(f(x)) = O(o(f(x)) = o(o(f(x))) = o(f(x))如何证明 f(x)=x,x小于等于0或-x,x大于0,g（x）=x+1,则f【g（x）】=? f(x)=2x-1,g(x)=x^2,则f[g(x)]=?,g[f(x)]=?,f[f(x)]=?,g[g(x)]=? 设f(x)=x^2 ,g(x)=2^x 则f[g(x)]= g[f(x)]=f[g(x)]= g[f(x)]= 1.已知求2.已知求注：（f o g)=f{g(x)} (g o f)=g{f(x)} 谢谢了! F[x]中,若f(x)+g(x)=3,则f(0)+g(0)=? 同阶无穷小量的表示方法?急! 还有f(x)=O(g(x))是什么意思?老师说f(x)=h(x)g(x)且h(x)是有界的则说f(x)=O(g(x)),老师讲的f(x)=O(g(x))且g(x)=O(f(x))时,f(x)和g(x)才是同阶的,而书上说f(x)和g(x)同阶表示为f(x)=O(g( 已知f'(x)=g(x),g'(x)=f(x),f(0)=1,g(0)=0,证f^2(x)+g^2(x)=1 f(g(x))=g(f(x))怎么证明