\(3x-\frac{1}{2}=\frac{5}{2}x+4\)

\(=>\frac{1}{2}x=\frac{1}{2}+4\)

\(=>\frac{1}{2}x=\frac{9}{2}\)

\(=>x=9\)

ủng hộ mik nha các bạn thân mến

9000 = IX

8000 = IIX

7000 = VII

6000 = VI 

Nếu đúng thì cho mình nhé 

\(A=1-\frac{1}{2}+\frac{1}{3}-\frac{1}{4}+\frac{1}{5}-\frac{1}{6}+...+\frac{1}{49}-\frac{1}{50}\)
\(A=\left(1+\frac{1}{3}+\frac{1}{5}+...+\frac{1}{49}\right)-\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{6}+...+\frac{1}{50}\right)\)

\(A=\left(1+\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+\frac{1}{5}+\frac{1}{6}+...+\frac{1}{49}+\frac{1}{50}\right)-2.\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{6}+...+\frac{1}{50}\right)\)

\(A=\left(1+\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+\frac{1}{5}+\frac{1}{6}+...+\frac{1}{49}+\frac{1}{50}\right)-\left(1+\frac{1}{2}+\frac{1}{3}+...+\frac{1}{25}\right)\)

\(A=\frac{1}{26}+\frac{1}{27}+\frac{1}{28}+...+\frac{1}{50}\)

\(A=\left(\frac{1}{26}+\frac{1}{27}+...+\frac{1}{30}\right)+\left(\frac{1}{31}+\frac{1}{32}+...+\frac{1}{40}\right)+\left(\frac{1}{41}+\frac{1}{42}+...+\frac{1}{50}\right)\)

\(A< \left(\frac{1}{25}+\frac{1}{25}+...+\frac{1}{25}\right)+\left(\frac{1}{30}+\frac{1}{30}+...+\frac{1}{30}\right)+\left(\frac{1}{40}+\frac{1}{40}+...+\frac{1}{40}\right)\)

                5 phân số 1/25                                 10 phân số 1/30                                 10 phân số 1/40

\(A< 5.\frac{1}{25}+10.\frac{1}{30}+10.\frac{1}{40}\)

\(A< \frac{1}{5}+\frac{1}{3}+\frac{1}{4}\)

\(A< \frac{1}{4}+\frac{1}{3}+\frac{1}{4}\)

\(A< \frac{1}{2}+\frac{1}{3}\)

\(A< \frac{5}{6}\)

\(A=1-\frac{1}{2}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{49}-\frac{1}{50}\)

\(=\frac{1}{2}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{49}-\frac{1}{50}\)

\(=\frac{5}{6}-\frac{1}{4}+\frac{1}{5}-\frac{1}{6}+...+\frac{1}{49}-\frac{1}{50}\)

\(=\frac{5}{6}+\left(\frac{1}{5}-\frac{1}{4}\right)+\left(\frac{1}{7}-\frac{1}{6}\right)+...+\left(\frac{1}{49}-\frac{1}{48}\right)-\frac{1}{50}\)

\(\frac{1}{5}-\frac{1}{4}< 0\)

\(\frac{1}{7}-\frac{1}{6}< 0\)

\(...\)

\(\frac{1}{49}-\frac{1}{48}< 0\)

\(\frac{5}{6}\) khi cộng với các số nhỏ hơn 0 thì giá trị nó sẽ giảm, đồng thời còn bớt đi \(\frac{1}{50}\)

Do đó \(A< \frac{5}{6}\)

A=124-5.|x-7|

Ta có: \(\left|x-7\right|\ge0\Rightarrow5.\left|x-7\right|\ge0\Rightarrow-5.\left|x-7\right|\le0\Rightarrow124-5.\left|x-7\right|\le124\)

Dấu "=" xảy ra <=> x - 7 = 0 <=> x = 7

B=1/3.|x+2|+4

Chỉ tìm đc GTNN

\(\left(-2\right)^{4x+2}=\frac{1}{64}\)

\(\Leftrightarrow\left(-2\right)^{4x+2}=\left(-2\right)^{-6}\)

\(\Leftrightarrow4x+2=-6\)

\(\Leftrightarrow x=-2\)

Thảo Lê Thị sao ra:(-2)^4x+1=1/64 được vậy