Question

1.tìm q biết:

a. 2 và 1/2 - (q - 1/2) = 3/5

b.1/3 x q - 1/5 x q =0,6

c. 3/5 - q : 1/2 = 1/7

Answer 1

a) \(2\frac{1}{2}-\left(q-\frac{1}{2}\right)=\frac{3}{5}\)

\(\Rightarrow q-\frac{1}{2}=2\frac{1}{2}-\frac{3}{5}=\frac{19}{10}\)

\(\Rightarrow q=\frac{19}{10}+\frac{1}{2}=\frac{12}{5}=2,4\)

\(\Rightarrow q=2,4\)

b) \(\frac{1}{3}\cdot q-\frac{1}{5}\cdot q=0,6\)

\(=q\cdot\left(\frac{1}{3}-\frac{1}{5}\right)=0,6\)

\(=q\cdot\frac{2}{15}=0,6\)

\(\Rightarrow q=0,6:\frac{2}{15}=\frac{9}{2}=4,5\)

\(\Rightarrow q=4,5\)

c) \(\frac{3}{5}-q:\frac{1}{2}=\frac{1}{7}\)

\(\Rightarrow q:\frac{1}{2}=\frac{3}{5}-\frac{1}{7}=\frac{16}{35}\)

\(\Rightarrow q=\frac{16}{35}\cdot\frac{1}{2}=\frac{8}{35}\)

\(\Rightarrow q=\frac{5}{35}\)

Ở câu b áp dụng phân phối giữa phép nhân vs phép trừ.