2 câu trả lời
Bài giải :
|x+11×2|+|x+12×3|+...+|x+199×100|=100x.
Mà do vế trái luôn :x>0
⇒
x+11×2+x+23+x+34+.....+x+199×100=100x.
Vế trái có 99x
x=11×2+12×3+13×4+...+199×100.
x=1-12+12-13+13-14+...+199-1100.
x=1-1100.
x=99100.
|x+11.2|+|x+12.3|+...+|x+199.100|=100x(1)
Do {|x+11.2|≥0|x+12.3|≥0....|x+199.10|≥0(∀x∈R)
→|x+11.2|+|x+12.3|+...+|x+199.100|≥0∀x∈R
Do đó : 100x≥0→x≥0
Khi đó (1) có dạng :
x+11.2+x+12.3+...+x+199.100=100x→(x+x+...+x)+(11.2+12.3+...+199.100)=100x→99x+(1−12+12−13+...+199−1100)=100x→99x+(1−1100)=100x→99x+99100=100x→−x=−99100→x=99100(Tm)
Vậy x=99100