CâuCâu 1. |2x-1|+|1-2x)=8
Câu 2. |2x2 +|x-5||=2x2 +5
Câu 3. Cho S=\(\frac{1}{2}\)+(\(\frac{1}{2}\))2 +(\(\frac{1}{2}\))3+(\(\frac{1}{2}\))4 +...+(\(\frac{1}{2}\))2020 +(\(\frac{1}{2}\))2021 . Chứng minh rằng S<1
Câu 4 . Cho A=1-\(\frac{3}{4}+\left(\frac{3}{4}\right)^2-\) \(\left(\frac{3}{4}\right)^3+\left(\frac{3}{4}\right)^4-...-\left(\frac{3}{4}\right)^{2020}+\left(\frac{3}{4}\right)^{2021}\)