Question

GTLN cua A=\(\sqrt{1-x}+\sqrt{1+x}\)

Answer 1

bang =2 khi 1-x=1+x=>x=0 dang dung bang dien thoai o truong thong cam

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Answer 2

\(A^2=\left(1-x\right)+\left(x+1\right)+2\sqrt{\left(1-x\right)\left(x+1\right)}\)

\(\le2+\left(1-x\right)+\left(x+1\right)=2+2=4\) (BĐT AM-GM)

\(A^2\le4\Rightarrow A\le2\)

Dấu "=" xảy ra khi ....