Toán A=2+/x+ $\frac{5}{6}$/ B=5+/ $\frac{2}{3}$ -x 18/07/2021 By Vivian A=2+/x+ $\frac{5}{6}$/ B=5+/ $\frac{2}{3}$ -x
Đáp án: ` A = 2 + |x +5/6|` Ta có ` |x+5/6| \ge 0` ` => 2+ |x+5/6| \ge 2` ` => A \ge 2` ` => A_{min} = 2` Dấu ` =` khi ` x + 5/6 = 0 => x= -5/6` ***** ` B = 5 + |2/3-x|` Ta có `|2/3 – x| \ge 0` `=> 5 + |2/3 – x| \ge 5` ` => B \ge 5` ` => B_{min} =5` Dấu `=` xảy ra khi ` 2/3 – x= 0 => x= 2/3` Trả lời
a) `|x+5/6|≥0` $→$ Dấu “=” xảy ra khi $x+\dfrac{5}{6}=0$ $→x=-\dfrac{5}{6}$ $→A_{min}=2+0=2$ Vậy $A_{min}=2$ khi $x=-\dfrac{5}{6}$ b) `|2/3-x|≥0` $→$ Dấu “=” xảy ra khi $\dfrac{2}{3}-x=0$ $→x=\dfrac{2}{3}$ $→B_{min}=5+0=5$ Vậy $B_{min}=5$ khi $x=\dfrac{2}{3}$ Trả lời
Đáp án:
` A = 2 + |x +5/6|`
Ta có ` |x+5/6| \ge 0`
` => 2+ |x+5/6| \ge 2`
` => A \ge 2`
` => A_{min} = 2`
Dấu ` =` khi ` x + 5/6 = 0 => x= -5/6`
*****
` B = 5 + |2/3-x|`
Ta có `|2/3 – x| \ge 0`
`=> 5 + |2/3 – x| \ge 5`
` => B \ge 5`
` => B_{min} =5`
Dấu `=` xảy ra khi ` 2/3 – x= 0 => x= 2/3`
a) `|x+5/6|≥0`
$→$ Dấu “=” xảy ra khi $x+\dfrac{5}{6}=0$
$→x=-\dfrac{5}{6}$
$→A_{min}=2+0=2$
Vậy $A_{min}=2$ khi $x=-\dfrac{5}{6}$
b) `|2/3-x|≥0`
$→$ Dấu “=” xảy ra khi $\dfrac{2}{3}-x=0$
$→x=\dfrac{2}{3}$
$→B_{min}=5+0=5$
Vậy $B_{min}=5$ khi $x=\dfrac{2}{3}$