a. \(y\text{×}\dfrac{1}{5}-\dfrac{2}{3}=\dfrac{1}{4}\)
\(y\text{×}\dfrac{1}{5}=\dfrac{1}{4}+\dfrac{2}{3}\)
\(y=\dfrac{11}{12}:\dfrac{1}{5}=\dfrac{55}{12}\)
b. \(\dfrac{8}{5}-y:\dfrac{1}{2}=1\)
\(y:\dfrac{1}{2}=\dfrac{8}{5}-1\)
\(y=\dfrac{6}{5}\)
c. \(y\text{×}\dfrac{3}{4}+y\text{×}\dfrac{1}{4}-y=99\)
\(y\text{×}\left(\dfrac{3}{4}+\dfrac{1}{4}-1\right)=99\)
\(y\text{×}0=99\) (vô lí)
=> Không có giá trị y nào thỏa mãn.
d. \(\dfrac{y}{2}+\dfrac{y}{3}+\dfrac{y}{6}=1\)
\(\dfrac{3\text{×}y+2\text{×}y+y}{6}=\dfrac{6}{6}\)
\(\Rightarrow3\text{×}y+2\text{×}y+y=6\)
\(y\text{×}\left(3+2+1\right)=6\) hay \(y\text{×}6=6\)
\(y=1\)
e. \(\dfrac{y}{2}-\dfrac{7}{3}=\dfrac{1}{6}\)
\(\dfrac{y}{2}=\dfrac{1}{6}+\dfrac{7}{3}=\dfrac{5}{2}\)
\(y=5\)
f. \(\dfrac{15}{y-2}=\dfrac{3}{7}\)
\(\dfrac{15}{y-2}=\dfrac{15}{35}\) \(\Rightarrow y-2=35\)
\(y=37\)
Các bài g, h còn lại bạn làm tương tự như bài f.
