Bỏ () Rồi tính nhé
 

4: \(D=x^2-2\cdot x\cdot\dfrac{1}{2}+\dfrac{1}{4}+\dfrac{3}{4}\)

\(=\left(x-\dfrac{1}{2}\right)^2+\dfrac{3}{4}\ge\dfrac{3}{4}\forall x\)

Dấu '=' xảy ra khi \(x=\dfrac{1}{2}\)

\(A=\left(x^2-6x+9\right)-7=\left(x-3\right)^2-7\ge7\\ A_{min}=7\Leftrightarrow x=3\\ B=\left(9x^2+6x+1\right)-4=\left(3x+1\right)^2-4\ge-4\\ B_{min}=-4\Leftrightarrow x=-\dfrac{1}{3}\\ C=\left(x^2-2\cdot\dfrac{5}{2}x+\dfrac{25}{4}\right)-\dfrac{9}{4}=\left(x-\dfrac{5}{2}\right)^2-\dfrac{9}{4}\ge-\dfrac{9}{4}\\ C_{min}=-\dfrac{9}{4}\Leftrightarrow x=\dfrac{5}{2}\\ D=\left(x^2-x+\dfrac{1}{4}\right)+\dfrac{3}{4}=\left(x-\dfrac{1}{2}\right)^2+\dfrac{3}{4}\ge\dfrac{3}{4}\\ D_{min}=\dfrac{3}{4}\Leftrightarrow x=\dfrac{1}{2}\)

\(E=3\left(x^2+2\cdot\dfrac{1}{3}x+\dfrac{1}{9}\right)-\dfrac{4}{3}=3\left(x+\dfrac{1}{3}\right)^2-\dfrac{4}{3}\ge-\dfrac{4}{3}\\ E_{min}=-\dfrac{4}{3}\Leftrightarrow x=-\dfrac{1}{3}\\ F=x^2-2x+1+x^2-4x+4+2021\\ F=2\left(x^2-3x+\dfrac{9}{4}\right)+\dfrac{4031}{2}=2\left(x-\dfrac{3}{2}\right)^2+\dfrac{4031}{2}\ge\dfrac{4031}{2}\\ F_{min}=\dfrac{4031}{2}\Leftrightarrow x=\dfrac{3}{2}\)

a) Ta có: MN⊥d, EF⊥d

=> MN//EF(từ vuông góc đến song song)

b) Ta có: \(\widehat{MPQ}=180^0-\widehat{MPb}=180^0-55^0=125^0\)(kề bù)

\(\Rightarrow\widehat{MPQ}=\widehat{NMc}=125^0\)

Mà 2 góc này đồng vị

=> PQ//MN

Mà MN//EF

=> PQ//EF

tìm minx max của biểu thức ạ

\(\Leftrightarrow a\sqrt{a}+b\sqrt{b}\ge\left(\sqrt{a}+\sqrt{b}\right)^2\)

\(\Leftrightarrow\left(\sqrt{a}+\sqrt{b}\right)\left(a-\sqrt{ab}+b-\sqrt{a}-\sqrt{b}\right)>=0\)(đúng)

T T F T T F

The Soup Kitchen, founded in 1986, is a resource for the homeless, elderly, lonely and poor inCentral London, providing free hot meals, clothes and toiletries, and creating a sense of belonging and community. Serving around 70 people a day from 10 am -12 noon on Monday, Tuesday, Thursday, Friday and Saturday, with the Clothes Closet open on alternate Mondays, four to five volunteers are required each morning to carry out this vital work.
 The Soup Kitchen is run by a Board of Trustees, a part-time Director and Kitchen Manager, three more staff and a team of volunteers. Support for The Soup Kitchen comes from individuals, corporations and trusts. Volunteers and donations (both financial and in-kind) are vital to support our work and enable us to continue this service to the community.

1. The Soup Kitchen is a non-profit organization. T
2. It provides free meals for people in need. T 
3. It opens five days a week from 10am to 12pm.  F 
4. Clothing is provided every Monday morning. T
5. The organization is funded by donations from individuals, corporations and trusts. T 
6. People can only donate money to the Soup Kitchen. F 

0,5m=5dm

45,2cm=4,52dm

a) 5        b)4,52          c)24,3       d) 24,5

a/ \(0,5m=5dm\)

b/ \(45,2cm=4,52dm\)

c/ \(2,43m=24,3dm\)

d/ \(2450mm=24,5dm\)