I use 'radical' here in both the original sense of 'addressing the root' and the newer, no doubt related sense of being 'extreme.'

我在此使用“radical”这个词，即指它的原始意义“根本的”，也指它的另一个意义‘极端的’。

youdao

Before such radical changes take root, two questions need to be answered.

在彻底完成这种根本性变革之前，需要回答两个问题。

youdao

We could make a start by being guided by people that understand the very root cause of our problems and have fresh, radical ideas as to their resolution.

我们可以作为一个起点，被人所为指导，因为他们了解我们的问题很根源，有新鲜的，以解决这些激进思想。

youdao

Brand's perspective is that mental illness is more at fault in the attack than the influence of radical Islam and that root causes must be analyzed, as well.

CNN: Opinion: Russell Brand: Don't blame Muslims

But the root causes of radical Islam - the range of issues that enabled al-Qaeda to recruit disaffected young Muslims to its cause - remain, for the most part, unaddressed.

BBC: Will Osama Bin Laden continue to haunt the US?

And now the entire region is threatened because of radical extremists who have taken root in Somalia, taking advantage of what they perceive to be a failing state, to use that as a base to launch attacks, most recently in Uganda.

WHITEHOUSE: Town Hall with Young African Leaders