25 x (n + 2) = 35 x (n + 1)
\(\Leftrightarrow\) 25 x n + 50 = 35 x n + 35
\(\Leftrightarrow\) 35 x n + 35 - 25 x n - 50 = 0
\(\Leftrightarrow\) 10 x n - 15 = 0
\(\Leftrightarrow\) 10 x n = 15
\(\Leftrightarrow\) n = \(\dfrac{3}{2}\) = 1,5
chắc là n mũ 2 và n mũ 1 nhỉ
\(25.n^2=30.n\)
\(25.n^2-30.n=0\)
\(n\left(25n-30\right)=0\)
\(=>n=0\) hoặc \(25n-30=0\)
+ \(25n-30=0\)
\(25n=30\)
\(n=1.2\)
Ta có: \(25\left(n+2\right)=30\left(n+1\right)\)
\(\Leftrightarrow25n+50=30n+30\)
\(\Leftrightarrow25n-30n=30-50\)
\(\Leftrightarrow-5n=-20\)
hay n=4
Vậy: n=4
Làm lại, em sai đề :
25 x (n + 2) = 30 x (n + 1)
\(\Leftrightarrow\) 25 x n + 50 = 30 x n + 30
\(\Leftrightarrow\) 30 x n + 30 - 25 x n - 50 = 0
\(\Leftrightarrow\) 5 x n - 20 = 0
\(\Leftrightarrow\) 5 x n = 20
\(\Leftrightarrow\) n = 4
