Toán A=(1-1/2).(1-1/3)x…x(1-1/9) hãy cm A<1 13/09/2021 By Vivian A=(1-1/2).(1-1/3)x…x(1-1/9) hãy cm A<1
$\text{A=(1-$\dfrac{1}{2}$)×(1- $\dfrac{1}{3}$)×……×(1- $\dfrac{1}{9}$)}$ $\text{A=$\dfrac{1}{2}$×$\dfrac{2}{3}$×…..× $\dfrac{8}{9}$}$ $\text{A=$\dfrac{1×2×….×8}{2×3×….×9}$}$ $\text{⇒A=$\dfrac{1×(2×….×8)}{(2×3×….×8)×9}$}$ $\text{⇒A=$\dfrac{1}{9}$}$ $\text{Vì $\dfrac{1}{9}$ <1}$ $⇒A<1$ Trả lời
CHÚC BẠN HỌC TỐT.
$\text{A=(1-$\dfrac{1}{2}$)×(1- $\dfrac{1}{3}$)×……×(1- $\dfrac{1}{9}$)}$
$\text{A=$\dfrac{1}{2}$×$\dfrac{2}{3}$×…..× $\dfrac{8}{9}$}$
$\text{A=$\dfrac{1×2×….×8}{2×3×….×9}$}$
$\text{⇒A=$\dfrac{1×(2×….×8)}{(2×3×….×8)×9}$}$
$\text{⇒A=$\dfrac{1}{9}$}$
$\text{Vì $\dfrac{1}{9}$ <1}$
$⇒A<1$