Áp dụng BĐT Min-cốp-xki:
\(A=\sqrt{\left(x+2\right)^2+2^2}+\sqrt{\left(1-x\right)^2+1^2}\ge\sqrt{\left(x+2+1-x\right)^2+\left(2+1\right)^2}=3\sqrt{2}\)
\(\Rightarrow A_{min}=3\sqrt{2}\) khi \(\left(x+2\right).1=2.\left(1-x\right)\Leftrightarrow x=0\)
Tìm Max, Min của
a.\(f\left(x\right)=\sqrt{x+1}+\sqrt{9-x}\)
b.\(f\left(x\right)=\sqrt{x}+\sqrt{2-x}+\sqrt{2x-x^2}\)
c.\(f\left(x\right)=x+\sqrt{8-x^2}+x\sqrt{8-x^2}\)
d.\(f\left(x\right)=\sqrt{x+2}+\sqrt{2-x}+\sqrt{4-x^2}\)
câu 1: lập bảng xét dấu để tìm nghiệm của bất pt sau:
a/\(4x^2-5x+1\ge0\)
b/\(3x^2-4x+1\le0\)
câu 2:
a/\(|x^2-3x+2|\le8-2x\)
b/\(x^2-5x+\sqrt{x\left(5-x\right)}+2< 0\)
c/\(\sqrt{8+2x-x^2}>6-3x\)
d/\(2\sqrt{1-\frac{2}{x}}+\sqrt{2x-\frac{8}{x}}\ge x\)
e/\(|x^2-4x+3|>2x-3\)
f/\(\sqrt{-x^2+6x-5}\le8-2x\)
g/\(x^2-8x-\sqrt{x\left(x-8\right)}< 6\)
h/\(3\sqrt{1-\frac{3}{x}}+\sqrt{3x-\frac{27}{x}}\ge x\)
GIẢI PHƯƠNG TRÌNH
1, ĐẶT ẨN PHỤ
A, \(\sqrt{1+x}+\sqrt{8-x}+\sqrt{8-7x+x^2}=3\)
b,\(x^2+x+6+2x\sqrt{x+3}=4\left(x+\sqrt{x+3}\right)\)
2, ĐÁNH GIÁ
a,\(\sqrt{x+1}+\sqrt{x+10}=\sqrt{x+2}+\sqrt{x+5}\)
b,\(\frac{x}{\sqrt{4x-1}}+\frac{\sqrt{4x-1}}{x}=2\)
Giải các bất phương trình sau:
1. \(\sqrt{5x+1}-\sqrt{4x-1}< 3\sqrt{x}\)
2. \(\sqrt{x+2}-\sqrt{3-x}< \sqrt{5-2x}\)
3 \(\dfrac{\sqrt{12+x-x^2}}{x-11}\ge\dfrac{\sqrt{12+x-x^2}}{2x-9}\)
4.\(\sqrt{x^2-8x+15}+\sqrt{x^2+2x-15}\le\sqrt{4x^2-18x+18}\).
Tìm Min
\(K=\sqrt{x^2+10x+26}+\sqrt{x^2+4x+4}\)
Giải các bất phương trình sau:
1) \(x^3+\left(3x^2-4x-4\right)\sqrt{x+1}\le0\)
2) \(\sqrt{2x^2-6x+8}-\sqrt{x}\le x-2\)
3) \(4\left(x+1\right)^2< \left(2x+10\right)\left(1-\sqrt{3+2x}\right)\)
4) \(4\sqrt{x+1}+2\sqrt{2x+3}\le\left(x-1\right)\left(x^2-2\right)\)
Hãy chứng min rằng :
1) \(\sqrt{a^2+b^2}+\sqrt{c^2+d^2}\ge\sqrt{\left(a+c\right)^2+\left(b+d\right)^2},\forall a,b,c,d\in R\)
2) \(\sqrt{4\cos^2x.\cos^2y+\sin^2\left(x-y\right)}+\sqrt{4\sin^2x.\sin^2y+\sin^2\left(x-y\right)}\ge2,\forall x,y\in R\)
giải bpt:
1. \(\frac{\sqrt{-3x^2+x+4}+2}{x}< 2\)
2. \(\sqrt{x^2-3x+2}+\sqrt{x^2-4x+3}\ge2\sqrt{x^2-5x+4}\)
3. \(\sqrt{x^2-8x+15}+\sqrt{x^2+2x-15}\le\sqrt{4x^2-18x=18}\)
4. 4(x+1)2 \(\ge\) (2x +10)( 1- \(\sqrt{3+2x}\))2
5. \(\sqrt{1+x}-\sqrt{1-x}\ge x\)
Tìm x:
a.\(\sqrt{4-\sqrt{4+x}}=x\)
b.\(4\left(\sqrt{x-1}-3\right)x^2+\left(13\sqrt{x+1}-8\right)x-4\sqrt{x-1}-3=0\)
c.\(\sqrt{2x-3}+2\sqrt{x-3}\ge3\sqrt[4]{2x^2+x-6}\)
