100 тренировочных задач #107 sqrt(2-x-x^2)+1=sqrt(x)-sqrt(x^2-x)

Whole-channel inclusion: Valery Volkov is an honest teaching channel (title sample + 3 transcripts read: All three samples lack transcripts, so the channel verdict relies on the prior title-sample assessment of consistent, non-clickbait math teaching content.); this title passed a strict title check (sonnet) after a labelling pass.