Question

So sánh A=3^18+2/3^19+10 và B=3^17+2/3^18+10

Answer 1

\(A\)\(=\dfrac{3^{18}+2}{3^{19}+10}\)

\(17A=\dfrac{3^{19}+6}{3^{19}+10}=1-\dfrac{4}{3^{19}+10}\)

\(B=\dfrac{3^{17}+2}{3^{18}+10}\)

\(17B=\dfrac{3^{18}+6}{3^{18}+10}=1-\dfrac{4}{3^{18}+10}\)

Vì \(\dfrac{4}{3^{19}+10}< \dfrac{4}{3^{18}+10}\)

⇒\(1-\dfrac{4}{3^{19}+10}\) \(>\) \(1-\dfrac{4}{3^{18}+10}\)

⇒\(A>B\)