\(\frac{x-12}{77}+\frac{x-11}{78}=\frac{x-74}{15}+\frac{x-73}{16}\)
\(\Leftrightarrow\left[\frac{x-12}{77}-1\right]+\left[\frac{x-11}{78}-1\right]=\left[\frac{x-74}{15}-1\right]-\left[\frac{x-73}{16}-1\right]\)
\(\Leftrightarrow\frac{x-12-77}{77}+\frac{x-11-78}{78}=\frac{x-74-15}{15}+\frac{x-73-16}{16}\)
\(\Leftrightarrow\frac{x-89}{77}+\frac{x-89}{78}=\frac{x-89}{15}+\frac{x-89}{16}\)
\(\Leftrightarrow\frac{x-89}{77}+\frac{x-89}{78}=\frac{x-89}{15}+\frac{x-89}{16}=0\)
\(\Leftrightarrow\left[x-89\right]\cdot\left[\frac{1}{77}+\frac{1}{78}-\frac{1}{15}-\frac{1}{16}\right]=0\)
\(\Leftrightarrow x-89=0\)
\(\Leftrightarrow x=89\)
Vậy x = 89
mik ko biết
mà nhìn như toán nâng cao ý
thỏ_con đây ko phải toán nâng cao đâu p/s : mk nghĩ thế :))
\(\frac{x-12}{77}+\frac{x-11}{78}=\frac{x-74}{15}+\frac{x-73}{16}\)
\(\frac{x-12}{77}-1+\frac{x-11}{78}-1=\frac{x-74}{15}-1+\frac{x-73}{16}-1\)
\(\frac{x-12-77}{77}+\frac{x-11-78}{78}=\frac{x-74-15}{15}+\frac{x-73-16}{16}\)
\(\frac{x-89}{77}+\frac{x-89}{78}=\frac{x-89}{15}+\frac{x-89}{16}\)
\(\left(x-89\right)\left(\frac{1}{77}+\frac{1}{78}+\frac{1}{15}+\frac{1}{16}\right)=0\)
Vì \(\frac{1}{77}+\frac{1}{78}+\frac{1}{15}+\frac{1}{16}\ne0\)
\(\Leftrightarrow x-89=0\Leftrightarrow x=89\)
Nhưng mik cũng học lớp 6 mà dạng toán này mik chưa học
