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\(a.A=\left(x-2\right)^2+\left(y+1\right)^2+1\ge1\forall x;y\) . " = " \(\Leftrightarrow x=2;y=-1\)
b.\(B=7-\left(x+3\right)^2\le7\forall x\) " = " \(\Leftrightarrow x=-3\)
c.\(C=\left|2x-3\right|-13\ge-13\forall x\) " = " \(\Leftrightarrow x=\dfrac{3}{2}\)
d.\(D=11-\left|2x-13\right|\le11\forall x\) " = " \(\Leftrightarrow x=\dfrac{13}{2}\)
\(A=0,5-\left|x-3,5\right|\le0,5\\ A_{max}=0,5\Leftrightarrow x-3,5=0\Leftrightarrow x=3,5\\ B=-\left|1,4-x\right|2=-2\left|1,4-x\right|\le0\\ B_{min}=0\Leftrightarrow1,4-x=0\Leftrightarrow x=1,4\)
\(A=-3x^2-5\left|y-1\right|+3\le3\)
Dấu ''='' xảy ra khi x = 0 ; y = 1
THAM KHẢO:
A= −3x2−5|y−1|+3 ≤ 3
Dấu ''='' xảy ra khi x = 0 ; y = 1
a: \(\left(x-2\right)^2>=0\)
\(\left|y-x\right|>=0\)
Do đó: \(\left(x-2\right)^2+\left|y-x\right|>=0\forall x,y\)
=>\(\left(x-2\right)^2+\left|y-x\right|+3>=3\forall x,y\)
=>A>=3 với mọi x,y
Dấu = xảy ra khi x-2=0 và y-x=0
=>x=2=y
b: \(\left|x+5\right|>=0\)
=>\(\left|x+5\right|+5>=5\)
=>B>=5 với mọi x
Dấu = xảy ra khi x+5=0
=>x=-5
c: \(\left|x-2010\right|>=0\)
=>\(-\left|x-2010\right|< =0\)
=>\(-\left|x-2010\right|+2012< =2012\)
=>\(C=\dfrac{2011}{2012-\left|x-2010\right|}>=\dfrac{2011}{2012}\forall x\)
Dấu = xảy ra khi x=2010
a) Ta có:
\(A=\left(x-2\right)^2+\left|y-x\right|+3\)
Mà: \(\left\{{}\begin{matrix}\left(x-2\right)^2\ge0\\\left|y-x\right|\ge0\end{matrix}\right.\)
\(\Rightarrow A=\left(x-2\right)^2+\left|y-x\right|+3\ge3\)
Dấu "=" xảy ra khi:
\(\left\{{}\begin{matrix}x-2=0\\y-x=0\end{matrix}\right.\)
\(\Rightarrow x=y=2\)
Vậy: \(A_{min}=3\Leftrightarrow x=y=2\)
b) Ta có:
\(B=\left|x+5\right|+5\)
Mà: \(\left|x+5\right|\ge0\)
\(\Rightarrow B=\left|x+5\right|+5\ge5\)
Dấu "=" xảy ra:
\(x+5=0\Rightarrow x=-5\)
Vậy: \(B_{min}=5\Leftrightarrow x=-5\)
c) Ta có:
\(C=\dfrac{2011}{2012-\left|x-2010\right|}\)
Mà: \(\left|x-2010\right|\ge0\)
\(\Rightarrow C=\dfrac{2011}{2012-\left|x-2010\right|}\ge\dfrac{2011}{2012}\)
Dấu "=" xảy ra khi:
\(x-2010=0\Rightarrow x=2010\)
Vậy: \(C_{min}=\dfrac{2011}{2012}\Leftrightarrow x=2010\)
\(A=\left|x-2018\right|-\left|x-2017\right|\le\left|x-2018-x+2017\right|=\left|-1\right|=1\)
Dấu "=" xảy ra <=> (x-2018)(x-2017) > 0
<=> \(\left[{}\begin{matrix}x>2018\\x< 2017\end{matrix}\right.\)
Vậy MaxA = 1 <=> \(\left[{}\begin{matrix}x>2018\\x< 2017\end{matrix}\right.\)
A = | x − 2018 | − | x − 2017 | ≤ | x − 2018 − x + 2017 | = | − 1 | = 1 Dấu "=" xảy ra <=> (x-2018)(x-2017) > 0 <=> [ x > 2018 x < 2017 Vậy MaxA = 1 <=> [ x > 2018 x < 2017