Tìm Min: B=x^2-2x+2016
Tìm Min = x^2 - 2x + 2016
Tìm Max = -x^2 +2x + 2016
x^2-2x+2016=(x-1)^2+2015>=2015
=> min của x^2-2x+2016=2015 khi x =1
-x^2+2x+2016=-(x-1)^2+2017=<2017
=> max -x^2+2x+2016 =2017 khi x=1
1. Tìm Min
a, 3x^2 + 5x
b, (2x-1)^2 - x^2
2.Cho x+y=2. Tìm Min A = x^2+y^2
3. tìm Min A = x^2 + 6y^2 + 4xy - 2x - 8y + 2016
Tìm min B=\(\frac{x^2-2x+2016}{x^2}\)
x khac 0
Bx^2=x^2-2x+2016
(1-B)x^2-2x+2016=0
\(\Rightarrow\Delta=1-4.\left(1-B\right).2016\ge0\Rightarrow1-4.2016+4.2016B\ge0\)
\(B\ge\frac{4.2016-1}{4.2016}=1-\frac{1}{4.2016}\)
GTNN(B)=1-1/(4.2016)
bắt hết các loại gió mùa
Tìm min B= \(\frac{x^2-2x+2016}{x^2}\)
Ta có:
\(B=\frac{x^2-2x+2016}{x^2}\Rightarrow2016B=\frac{2015x^2+\left(x^2-2.2016x+2016^2\right)}{x^2}=2015+\frac{\left(x-2016\right)^2}{x^2}\ge2015\)
Dấu "=" xảy ra khi \(\frac{\left(x-2016\right)^2}{x^2}=0\Rightarrow x=2016\)
\(\Rightarrow2016B_{min}=2015\Rightarrow B_{min}=\frac{2015}{2016}\) khi \(x=2016\)
Tìm min B= \(\frac{x^2-2x+2016}{x^2}\)
Tìm min B=\(x^2-2x+2016\)
Tìm min của các biểu thức sau:
A=3x^2 - 6x - 1
B=x^2 - 2x + y^2 - 4y + 2016
C=(x-1).(x+2).(x+3).(x+6)
LÀM dùm bn 1 câu khó nhất nhé;
B = (x-1)2 + ( y -2)2 +2016 -1 -4
GTNN B = 2011
A=3(x^2-2x-1/3)
=3(x-1)^2 -4/3
ta có (x-1)^2 >= 0
suy ra a>= 0-4/3
dấu bằng xảy ra khi x-1=0
x=1
vậy giá trị nhỏ nhất của A là -4/3 khi x=1
B=(x-1)^2 +(y-2)^2 +2016-(4+1)
ta có (x-1)^2 lớn hơn hoặc bằng 0
(y-2)^2 lớn hơn hoặc bằng 0
suy ra B lớn hơn howcj bằng 0+0+2011
đấu bằng xảy ra khi x-1=0 suy ra x=1
y-2 =0 suy ra x=2
vậy GTNN của B là 2011 khi x=1;y=2
1. Tìm Min hoặc Max :
a) A = | x + 1| + 2016
b) B = 2017 - | 2x - 1/3|
c) C = | x + 1| + | y + 2| + 2016
d) D = -| x + 1/2| - | y - 1| +10
2. Tìm x, biết:
a) ( x+1)( y + 2) = 0
b) ( x + 2)( x - 3) > 0
c) ( x + 1/2) = 3
d) | x + 1| < 2016
e) | x - 1/2| > 5
Câu 1:
a)A=|x+1|+2016
Vì |x+1|\(\ge\)0
Suy ra:|x+1|+2016\(\ge\)2016
Dấu = xảy ra khi x+1=0
x=-1
Vậy MinA=2016 khi x=-1
b)B=2017-|2x-\(\frac{1}{3}\)|
Vì -|2x-\(\frac{1}{3}\)|\(\le\)0
Suy ra:2017-|2x-\(\frac{1}{3}\)|\(\le\)2017
Dấu = xảy ra khi \(2x-\frac{1}{3}=0\)
\(2x=\frac{1}{3}\)
\(x=\frac{1}{6}\)
Vậy Max B=2017 khi \(x=\frac{1}{6}\)
c)C=|x+1|+|y+2|+2016
Vì |x+1|\(\ge\)0
|y+2|\(\ge\)0
Suy ra:|x+1|+|y+2|+2016\(\ge\)2016
Dấu = xảy ra khi x+1=0;x=-1
y+2=0;y=-2
Vậy MinC=2016 khi x=-1;y=-1
d)D=-|x+\(\frac{1}{2}\)|-|y-1|+10
=10-|x+\(\frac{1}{2}\)|-|y-1|
Vì -|x+\(\frac{1}{2}\)|\(\le\)0
-|y-1| \(\le\)0
Suy ra: 10-|x+\(\frac{1}{2}\)|-|y-1| \(\le\)10
Dấu = xảy ra khi \(x+\frac{1}{2}=0;x=-\frac{1}{2}\)
y-1=0;y=1
Vậy Max D=10 khi x=\(-\frac{1}{2}\);y=1
Bài 1:
a)Ta thấy: \(\left|x+1\right|\ge0\)
\(\Rightarrow\left|x+1\right|+2016\ge0+2016=2016\)
\(\Rightarrow A\ge2016\)
Dấu = khi x=-1
Vậy MinA=2016 khi x=-1
b)Ta thấy:\(\left|2x-\frac{1}{3}\right|\ge0\)
\(\Rightarrow-\left|2x-\frac{1}{3}\right|\le0\)
\(\Rightarrow2017-\left|2x-\frac{1}{3}\right|\le2017-0=2017\)
\(\Rightarrow B\le2017\)
Dấu = khi x=1/6
Vậy Bmin=2017 khi x=1/6
c)Ta thấy:\(\begin{cases}\left|x+1\right|\\\left|y+2\right|\end{cases}\ge0\)
\(\Rightarrow\left|x+1\right|+\left|y+2\right|\ge0\)
\(\Rightarrow\left|x+1\right|+\left|y+2\right|+2016\ge0+2016=2016\)
\(\Rightarrow D\ge2016\)
Dấu = khi x=-1 và y=-2
Vậy MinD=2016 khi x=-1 và y=-2
d)Ta thấy:\(\begin{cases}-\left|x+\frac{1}{2}\right|\\-\left|y-1\right|\end{cases}\le0\)
\(\Rightarrow-\left|x+\frac{1}{2}\right|-\left|y-1\right|\le0\)
\(\Rightarrow-\left|x+\frac{1}{2}\right|-\left|y-1\right|+10\le0+10=10\)
\(\Rightarrow D\le10\)
Dấu = khi x=-1/2 và y=1
Vậy MaxD=10 khi x=-1/2 và y=1
a) ( x + 1 )( y + 2 ) = 0
\(\Rightarrow\) x + 1 = 0 hoặc y + 2 = 0
+) x + 1 = 0 \(\Rightarrow\) x = -1
+) y + 2 = 0 \(\Rightarrow\) y = -2
Vậy x = -1; y = -2
tìm min B=\(\dfrac{x^2-2x+2016}{x^2}\)
\(B=\dfrac{x^2-2x+2016}{x^2}\\ \\ =\dfrac{x^2}{x^2}-\dfrac{2x}{x^2}+\dfrac{2016}{x^2}\\ \\ =1-\dfrac{2}{x}+\dfrac{2016}{x^2}\\ =\dfrac{2016}{x^2}-\dfrac{2}{x}+\dfrac{1}{2016}+\dfrac{2015}{2016}\\ =\left(\dfrac{2016}{x^2}-\dfrac{2}{x}+\dfrac{1}{2016}\right)+\dfrac{2015}{2016}\\ =2016\left(\dfrac{1}{x^2}-\dfrac{1}{1008x}+\dfrac{1}{2016^2}\right)+\dfrac{2015}{2016}\\ =2016\left(\dfrac{1}{x}-\dfrac{1}{2016}\right)^2+\dfrac{2015}{2016}\)
Do \(2016\left(\dfrac{1}{x}-\dfrac{1}{2016}\right)^2\ge0\forall x\)
\(\Rightarrow B=2016\left(\dfrac{1}{x}-\dfrac{1}{2016}\right)^2+\dfrac{2015}{2016}\ge\dfrac{2015}{2016}\forall x\)
Dấu "=" xảy ra khi:
\(2016\left(\dfrac{1}{x}-\dfrac{1}{2016}\right)^2=0\\ \Leftrightarrow\dfrac{1}{x}-\dfrac{1}{2016}=0\\ \Leftrightarrow\dfrac{1}{x}=\dfrac{1}{2016}\\ \Leftrightarrow x=2016\)
Vậy \(B_{Min}=\dfrac{2015}{2016}\) khi \(x=2016\)