Question

Số a > 0 thỏa mãn: \(\frac{15}{a}=\frac{a-1}{28}\) là a =......

Answer 1

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https://hoc24.vn/hoi-dap/question/172644.html

Answer 2

\(\frac{15}{a}=\frac{a-1}{28}\)

\(\Rightarrow15.28=\left(a-1\right)a\)

\(\Rightarrow420=\left(a-1\right)a\)

\(\Rightarrow20.21=\left(a-1\right)a\)

\(\Rightarrow a=21\)