\(\text{(1/15 + 1/35 + 1/63) x X = 1}\)
\(\left(\frac{2}{21}+\frac{1}{63}\right)\cdot x=1\)
\(\frac{1}{9}\cdot x=1\)
\(x=1:\frac{1}{9}\)
\(x=9.\)
Ta có: \(\left(\frac{1}{15}+\frac{1}{35}+\frac{1}{63}\right).x=1\)
\(\Rightarrow\frac{1}{9}.x=1\)
\(\Rightarrow x=1:\frac{1}{9}\)
\(\Rightarrow x=9\)
Vậy x = 9
Ta có:
\(\left(\frac{1}{15}+\frac{1}{35}+\frac{1}{63}\right).x=1\)
\(\Rightarrow\left(\frac{1}{3.5}+\frac{1}{5.7}+\frac{1}{7.9}\right).x=1\)
\(\Rightarrow\left(\frac{1}{3.5}+\frac{1}{5.7}+\frac{1}{7.9}\right).2x=2\)
\(\Rightarrow\left(\frac{2}{3.5}+\frac{2}{5.7}+\frac{2}{7.9}\right).x=2\)
\(\Rightarrow\left(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}\right).x=2\)
\(\Rightarrow\left(\frac{1}{3}-\frac{1}{9}\right).x=2\)
\(\Rightarrow\frac{2}{9}.x=2\)
\(\Rightarrow x=2:\frac{2}{9}=9\)
Vậy x = 9