A thuộc hàm số y=\(\dfrac{1}{2}x^2\)

mà x_A=2=>y_A=\(\dfrac{1}{2}.4=2\)=>A(2;2)

B thuộc hàm số y=x²

mà x_B=2=>y_B=4=>B(2;4)

Mark the letter A, B, C, or D on your answer sheet to indicate the underlined part that needs correction in each of the following questions.

(A) Overpopulation is (B) a short way to lead to (C) poor. (D) illiteracy, and social evils.

A. Overpopulation 

B. a short way

C. poor

D. illiteracy

AD bất đẳng thức Cauchy Schwarz, ta có

P=\(\dfrac{1}{a^2+b^2+1}+\dfrac{1}{2ab}\)\(\ge\dfrac{\left(1+1\right)^2}{a^2+2ab+b^2+1}\)=\(\dfrac{4}{\left(a+b\right)^2+1}\)(*)

mà a+b\(\le1\)=>(*)\(\ge\)\(\dfrac{4}{1+1}=2\)